"For, verily, Thine invisible and inaccessible Self can never be known; Thine unalloyed Essence can never be described. “The way is barred, and all seeking rejected.” "

 
... "O Lord! The innermost reality of understanding in this contingent realm is, in its essence, utterly powerless to grasp even a single one of the mysteries of the All-Merciful, inasmuch as all understanding encompasseth that reality in the realm of existence that is comprehensible. How, then, could that which is contingent comprehend the Ancient Mystery unless the Ancient be encompassed by the contingent world? And how could this be possible, given that the encompassing one is greater than that which is encompassed, and the knower thoroughly comprehendeth that which is the object of knowledge? This being the case, how then can there be a path to Thee; how can there be a way to the Kingdom of Thy sanctity? Naught are we but mere helplessness and poverty in the face of the mysteries of creation, let alone before the sublime Reality, which is inaccessible to the realm of idle fancies and thoughts!

Thou hast, nevertheless, through Thine inestimable grace and Thy resplendent bounty, and by virtue of Thy mercy that hath surpassed the whole of creation, fashioned a luminous Reality, a heavenly Being, a divine Essence—Whom Thou hast ordained to be a mirror, stainless and gleaming, that speaketh of the unseen world, that deriveth grace from that realm, and that shineth resplendently and copiously with the outpourings of those favours upon the entire creation. And this Thou hast done so as to deliver Thy sincere servants from the worship of idle fancies engraved even on the hearts of the mystic knowers. For verily, all Thy servants, O my Lord, except such as Thou hast chosen as Thine own, whilst communing with Thee, or bowing down in worship before Thee, conceive a fictitious reality comprehensible to their thoughts and minds. And thus do they worship it whilst immersed in the seas of idle fancies and vain imaginings. For, verily, Thine invisible and inaccessible Self can never be known; Thine unalloyed Essence can never be described. “The way is barred, and all seeking rejected.”¹²²

To whatever heights the most brilliant mind may soar, it can grasp no more than a mere token of the mystery of creation, a token which Thou hast deposited within the reality of all things. This, indeed, is the highest summit of comprehension to which those who inhabit the visible realm may hope to ascend, and even the manifold aspects of that token far transcend all comprehension in the realm of ascent." ...

(Light of the World: Selected Tablets of ‘Abdu’l-Bahá, #72, part 2)
www.bahai.org/r/830593592