God is beyond any rational explanation of Him.
>Nevertheless, we ought not to neglect the
mystical dimension of Thomas’ life. In his early
work, The Commentary on the Sentences of Peter
Lombard, he writes, ‘We know God most perfectly
in the present life when we realise him to be above all that our intellect can conceive; and thus we are joined to him as one unknown.’
>Sentences 4, 49, 2, 1 ad 3, translated Rocca, p. 56.
>In the Commentary on the Sentences, he wrote: When we proceed into God through the way of negation, first we deny of Him all corporeal realities; and next, even intellectual realities as they are found in creatures, like goodness and wisdom, and then there remains in our understanding only that God exists and nothing further, so that it suffers a kind of confusion. Lastly, however, we even remove from him his very existence, as it is in creatures, and then our understanding remains in a certain darkness of ignorance according to which, in this present state of life, we are best united to God, as Dionysius says, and this is a sort of thick fog in which God is said to dwell. (Sentences 1, 8, 1, 1, ad 4, translated Rocca, p. 65.)
>At the end of his life, when he stopped writing following an experience presumed in the tradition to have been mystical, Brother Reginald tried to persuade him to return to work to complete the Summa Theologiae, he simply said, ‘All I have written is straw.’
>Andrew Murray – Unknowability of God
Thinking you understand or really know God's nature is a proof of ignorance, of confusion between some human knowledge and His infinity. God's nature is beyond human comprehension.
That's what I was responding the infatuated rationalist that were thinking he understood the origin of the universe. Because that would imply this cause is determinated and thus can't be the first uncaused cause.
Not sure if you will understand though.