Despite the "Philosopher's Stone" bind rune is made of two halves, we speak about three phases overlapping each other, and you can see three vertical axes there.

Let's now find out what is happening in the middle one, and it's a lot.

Once Fire and Water are separated into individual forces, they can now interact.
There is now an "egg" of Emptiness in between, where this interaction takes place - Imgwaz.

We already filled it with Water and Fire, and now we hold it vertically with the left hand of Water from the top and the right hand of Fire from the bottom.

You hold the egg of the universe in front of yourself with a single vertical axis.

It's now your job to incubate this egg of the universe allow Water and Fire into this egg evenly and watch what's happening there.

Eihwaz Rune

Eihwaz means "Yew," and this tree was significant for Norse people from a practical perspective—the best bows were made of it because of its flexibility and resilience. At the same time, yew was rare, especially large and straight enough pieces suitable for bow crafting, so yew wood was expensive and was even a subject of importation. This unique combination of properties and its rarity adds value to the Yew.

I suggest "Bow" and "Archery" as secondary meanings for the Eihwaz rune. From primary sources of Norse Tradition, we know about the direct connection between yews and Ullr, the god of Archery, Hunting, and Skiing. Ullr was also known as a great warrior.

Due to the rarity of Yew, the second-best wood for crafting bows was Ash. Yggdrasil, the grand tree that connects all the worlds in the universe, is also Ash according to the Eddas. So yet another secondary but significant connection we can establish between Eihwaz and Yggdrasil, which is never stated explicitly in historical sources but is often considered by scholars.

From an alchemical perspective, Eihwaz is an iterative process of recycling and refining raw Earth not yet "processed" by pushing it down to Fire for "remelting" — this is the meaning of the bottom-left descending bar. If we think about a tree as a living organism - it gets "secondary" earth, the soil, left by life, and brings it back to the life cycle.

When a portion of raw Earth is pushed down, the next part of the rune is a vertical bar of Simultaneity — it works as a rebalancing of all 5 levels. Since the amount of Earth in the egg was reduced, more fresh raw Fire arrives instead.

But most importantly vertical bar of Eihwaz is the backbone of the entire universe! It connects opposites and holds everything in the right places.

The last part of the rune is the top-right descending bar which adds more Water into the system, and the entire alchemical process advances. It's a secret yet, but later you will find, how this descent of the Water is not just refreshing resources. It's a guide.

Doing the Tree

Feel your hands now.
You see your right hand of Fire supports the egg from the bottom and your left hand of Water covers it from the top:

You can now feel why Eihwaz is the rune of protection - you are both parents Fire and Water.

• Tune into the Earth somewhere on the level of your belly and down. Feel it not only in yourself but also in the world around you.
• Slowly breathe out and along with this exhalation, slide the energy of Earth down deeper to the world of Fire, somewhere below your feet.
  This is the bottom-left descending bar of the rune.
• During the small pause after that notice, you feel a little extra pressure in your head. It's because you changed the balance in your system. You reduced Earth so new fresh Fire arrived instead.
• Make a gentle slow inhale and feel your entire vertical axis which stands across all the levels starting from Fire, through Earth, Emptiness in the middle, Air, and Water on the top. This is a vertical bar of the Eihwaz rune.
• After doing so you will find yourself on the way to a new balance and that small extra pressure steps down from the head.
• With a second slow relaxed exhalation, let the Water fall onto your head and flow down through yourself. This last step is the last, top-right descending bar.

Breathing helps to manage attention, and doing Eihwaz step by step helps understand each of its aspects. But after some practice, we want and can do everything as a single steady holistic process, not dependent on breathing and without causing temporal pressure and energy fluctuations.
We want and can achieve true balance.

Balance both static, as represented by the vertical axis of simultaneity.
And dynamic, as represented by two diagonal bars, compensating continuous changes made by each other.

When you catch this triple state of Eihwaz by holding an energy egg in your hands, notice how the vertical axis of Eihwaz resonates with your vertical axis, so you may start feeling you are holding yourself in your hands. This bigger you, who holds you between palms, probably longer than you think, and watching your life, who is it?

We are trees

Ask and Embla, the first two humans, were created by three gods from trees.
Ask's name means Ash tree, but the etymology of Embla's name is not so clear.

In Völuspá, we read:

17. Until there came three
    mighty and benevolent
    Æsir to the world
    from their assembly.
    They found on earth,
    nearly powerless,
    Ask and Embla,
    void of destiny.

18. Spirit they possessed not,
    sense they had not,
    blood nor motive powers,
    nor goodly colour.
    Spirit gave Odin,
    sense gave Hoenir,
    blood gave Lodur,
    and goodly colour.

In Prose Edda:

When the sons of Borr were walking along the sea-strand, they found two trees, and took up the trees and shaped men of them: the first gave them spirit and life; the second, wit and feeling; the third, form, speech, hearing, and sight. They gave them clothing and names: the male was called Askr, and the female Embla, and of them was mankind begotten, which received a dwelling-place under Midgard.

I found this story to be very true, and here is how you can experience it yourself.

Find a partner for doing this exercise.
Sit opposite each other and look into each other's eyes for a long time, without stopping.
You can blink and look away at first but continue.
Gradually, the face will begin to distort and freeze, and only the gaze will remain.
As if a tree with eyes.

The very principle of gaze is the same for everyone, as is consciousness.
Personalities are different, characters, knowledge, experience, and so on, but all this is just a unique pattern on the bark of a tree.
The color and shape of the eyes, emotions, and feelings, even Fire and Water we had in our eyes - this is still a frame around the window. If you grasp the principle of gaze, you will feel it in yourself and everyone around you.

People are different, but someone always looks through the eyes.

Tiwaz Rune

On dark nights, it is easy to get lost. But every human has a built-in compass, an arrow always pointing upward to the guiding north star, the only star that remains constant in the sky. It's a quiet but firm inner voice, it tells us the right direction. When it speaks - the north star is shining in the center of our forehead.

It is the Tiwaz rune:

It is named after the god Týr, the one-handed Norse god of war, honor, faith, fame, justice, and protection, who sacrifices his right hand placing it in the wolf Fenrir's mouth to let other gods bind him.

He is often associated with the Roman god Mars, who, contrary to the Greek Ares, was not seen as a destructive and destabilizing force but rather a god protector of peace and had a paternal role.
Týr in turn has an even stronger incline towards Order.

The Tiwaz name itself, if viewed from an etymology perspective, seems to be connected to Proto-Germanic tīwaz, meaning "a god, a deity," and to Proto-Indo-European deywós, meaning 'celestial, heavenly one'.

Tiwaz is one of the few runes explicitly mentioned in the sources as having direct magical application, specifically the rune of victory.

In the Old English runic poem, this rune is associated with a guiding star which is ever on its course over the mists of night and never fails.

Tiwaz is extremely powerful and useful both as a stand-alone practice and as part of the alchemical process.

To do Tiwaz properly one needs to master all the aspects of Isa because we will use it as a starting state.

• Stand or sit comfortably, and close your eyes.
• Hold both palms upward as if you are holding two balls.
• Concentrate on your palm's energy centers to activate them. You can help yourself by breathing through palm centers and even tickle them by touching them delicately with the spiral movement of pinched fingers of another hand.
• Raise the Fire in your right hand and invite the Water to the left one.
• Slowly make a "prayer" gesture, keeping a layer of emptiness between your palms and feel the entire vertical axis from the bottom to the top simultaneously.

So now you feel Isa as the spear of Emptiness between your palms.

• Slowly breathe in.
• While inhaling, as suggested by the ascending bar of the Tiwaz rune, transit your focus of attention from your expanding chest, the level of Air, upward through your head and above to the level of Water.
• Hold breathing for a moment and refresh the feeling of your entire vertical axis which starts from the ground, goes along your spine and center of your head crown, and upward beyond your body to the world of Water where your breath just finished.
• Slowly breathe out.
• While exhaling, as suggested by the descending bar of the Tiwaz rune - transit your focus from the top world of the Water back to the Air level of your chest.

Repeat calmly as long as you want.

After some practice, you can switch from pulsating mode to the mode of continuous stream by detaching the practice from breathing. Just keep these ascending and descending streams in parallel with your vertical axis.

Notice how in the middle of your forehead appears a buzzing feeling of activation similar to the feeling of activated hands. This is your guiding star.
With your closed eyes, you may see its glow on the firmament, the inner side of your skull. It will guide you through the dark times and will help you to distinguish true from false and right from wrong.

To hear this voice and see this light you need to be honest with yourself and have a light heart, you need to be strong by staying in the very center of yourself, the only point in the entire universe you truly can rely on.

Tiwaz rune guides you and gives you enough strength and courage for that, but to find your center and balance yourself against it is quite a challenge itself, and this is why we need the next rune.

Algiz Rune

When the Water meets the Fire in the empty cavity of Ingwaz, it evaporates into clouds of the Air.
You can feel these clouds as a pain in your chest when something hits your ego.
You also can feel it as smoke or exhaust in your chest, when your ego inflates disproportinally.

The rune name Algiz is considered to have two main alternative meanings: "Elk" or "Protection". And both make sense, so why choose?

Anglo-Saxon rune poem tells about "elk-sedge":

The Elk-sedge usually lives in the fen,
growing in the water. It wounds severely,
staining with blood any man
who makes a grab at it.

There is an idea of killing/dissolving the ego in various spiritual traditions and teachings, but it's wrong to understand it in a destructive "amputational" way.

If there is an ego, then there is some purpose for it. Balancing, centering the ego against your essence, learning to always keep this equilibrium, and never falling into self-aggrandizement or self-deprecation - that's the way for a tightrope walker to the other side. If you cut the rope - you aren't getting anywhere.
Don't fight with ego, use your Faith to transform it into the clear soul.

Algiz rune does exactly that:

• Collect raw heavy dark and opaque clouds to the very center. You can associate this step with exhalation and descending focus of your attention from the breast down to the center part around the solar plexus, so you pump it into the center.
• Hold your breath, tune into vertical of simultaneity, and let them transmute by extra pressure from above and heat from below.
• Breathe it back from the center into the upper level of Air, your breast, but you now will feel its clean light blue sky, not leaden clouds.

To help yourself preserve even more attention, use a gesture of open palms with wrists placed close to each other and fingers pointed upward and outside, so the left hand will receive Air from the top left area and send it down to the solar plexus and right hand will direct it from the center to the top-right area.

The center of the Philosopher's Stone is the most mysterious place and it takes a lot to reach an understanding of what's happening there, that's why so many runes prescribe actions around the center from different perspectives. We already know the Ingwaz rune and we know that the center is a place where raw Fire and Water meet each other in the pocket of Emptiness. When it just happens there is a lot of steam, smoke, and clouds in the upper part. At the same time Fire in the lower part also experiences the dramatic process of cooling down, solidification, and loss of brightness. It feels like losing your power.

But you need to believe in yourself at this point, you need to trust the process. There is a fine thread between the divine spark in your very center and the guiding star at the very top. Very thin, straight, and only strong enough to let you pass. At first, you will slide off and fall, again and again. It's OK, just listen for your true self, just trust - and always get back to the center. At first baby learns to stay, then it learns to walk. All the way baby falls many times but something makes him try again and again.

So we have the first three runes in a row in the second phase of creation: Eihwaz, Tiwaz, and Algiz.
Together they give you a key to unlock the secret of the Philosopher's Stone: