On that which is (essentially) absent.

[Glenn Scheper]

For each group the bayyinah comes in an appropriate mode: to the seeker as 
direct confirmation from God, annihilating him in contemplation, while to the 
philosopher or theologian in the form of the writings and proofs of the 
gnostics.

The Abode of which we have spoken in this book is the Abode of "annihilation" 
and of "the rising of the Suns", and it possesses the degree of the Ihsân by 
which He sees you, not that by which you see Him.

It is at this station that the one who professes unification (ittihâd)[11] falls 
into error: for this person, seeing the journeying of the One through the 
imaginary degrees so that the names differ in accordance with the various 
degrees, does not see any number except the One and Only (ahad), and therefore 
he professes identity. Now if He manifests in His Name (One), He does not 
manifest in His Essence (dhât) as well except in His own private degree which is 
the Oneness (wahdâniyya)[12], so that in whatever degree He is manifest in His 
Essence, He does not manifest His (own) Name. He is named in that degree by that 
which the reality of the degree gives to Him, so that it is through His Name in 
that degree that there is extinction, and it is through His Essence that there 
is subsistence. Therefore if you say "One" (wâhid), everything other than He is 
annihilated through the reality of that name; and if you say "two", its 
essential reality ('ayn) manifests through the being of His Essence, of the One, 
in that degree, not through His Name (One), and His Name (One) denies the 
existence of this degree, whereas His Essence does not.

It is established that the alif in "tarâhu" is for the sake of His 
manifestation, because of the vision's dependence upon it. If he had eliminated 
it and said "tarahu", the vision would not occur because the pronoun ha in the 
word "tarâhu" denotes the one who is absent, and the absent one cannot be seen, 
and if the alif had been eliminated, then He would be seen without vision, and 
that cannot occur. So that is why the alif was mentioned. As for the wisdom of 
maintaining the pronoun ha, the meaning given is that the words "if you are not, 
you see Him" point to the fact that while you see by the existence of the alif 
you do not say "I have encompassed", for He, the Most High, is too majestic and 
glorious to be encompassed, and such a thing would not be possible. So the ha 
exists as the pronoun of that which is absent from you during the vision of the 
Reality of the Truth (haqîqatu-l haqq), which acts like a witness for you of the 
impossibility of encompassing (Him).
  -- http://www.ibnarabisociety.org/articles/kitabalfana.html
  Kitâb al-fâna' fi-l mushâhadah