Mysteries of the Bahir: Alef and Bet

Sometimes, Torah is so mysterious I don't know where to begin talking about it. But with meditation, sometimes I can find an answer. Here's one thing that stumped me:

What does the Bet (ב) resemble? It is like a man, formed by G-d with wisdom. He is closed on all sides, but open in front.
The Alef (א), however, is open from behind.
This teaches us that the tail of the Bet is open from behind. If not for this, man could not exist.
Likewise, if not for the Bet on the tail of the Alef, the world could not exist. 

~ The Bahir, #15

After an hour or so of thinking about it, an idea dropped in:

What does the Bet (ב) resemble? It is like a man, formed by G-d with wisdom. He is closed on all sides, but open in front.

A person must remain focused on his goal: to move forwards. This implies limiting distractions. He must "close himself on all sides, but remain open in front" in the direction of his goal.

The Alef (א), however, is open from behind!

But isn't our goal to expose unity? Might it not be argued that to unify the opposing forces of the world into one (the numerical value of Alef), even the energies opposite of "forwards" must be absorbed, harnessed and integrated? Shouldn't we take the forces of darkness and turn them to light?

This teaches us that the tail of the Bet is open from behind.

That may be so, but only after the fact. Do not seek to strengthen these energies; but if one finds oneself entangled with them, one must seek the good in them and return them to light.

If not for this, man could not exist.

Returning things to Light is the purpose of man's creation, and how he can be greater than the angels: by revealing light from the darkness itself (Igeres HaKodesh, end of ch. 12). Without this, there is no advantage or purpose to man's existence, and G‑d would not have created him. (Yet, his primary efforts must be directed towards the Luminary Itself, and attaching to Him; with out this, one will lose sight of his mission.)

Likewise, if not for the Bet on the tail of the Alef, the world could not exist. 

We can similarly how the world exists. If the potential for a "second" did not exist, symbolized by the Bet (with a numerical value of two), the absolute unity of Alef would dominate. This is the light that preceded Creation, which would obliterate any creation that saw it; the absolute one-ness that tolerates no otherness. By partnering a Bet with the Alef, otherness was allowed to exist, and the world was created.

I'll finish off with a promise from the Gemara:

If a person says to you, "I strove and I found not" - don't believe him.
"I strove not, yet I found" - don't believe him.
"I strove and I found" - believe him.

~ Megillah 6b