The Thirumaalai is a set of 45 paasurams composed by Sri Tondaradippodi Azhwar.
It is said (quite aptly) that "Thirumaalai ariyaar, Thirumaalai ariyaar" i.e those who do not know the Thirumaalai, do not know the Lord Sriman Narayana.
In this set of paasurams, Azhwar says, "Maasatraar manathuLLaanai vaNangi naam iruppathallaal paesathaan avathundo pedhai nenjae nee sollaai".
Azhwar says that the Lord can never be comprehended by those who try to understand Him through their intellect. You can analyse and discuss about the nature of the Lord endlessly, and yet you will come nowhere near understanding Him. Only those who understand the futility of comprehending Him through their intellect and surrender unto Him, actually comprehend His nature and glories to a certain extent. The Lord cannot be grasped by the intellect, rather we can only align ourselves with Him through surrender, and in the process, get some understanding of His glories and His nature.