Wow, My "Truth" is just as true as your "Truth". How convenient.
That is not what I said.
What I said is that our ability to perceive the essence of another person or thing outside ourselves is conditioned by the quality our faculties.
A mentally challenged person may never understand that the square root of 34,969 is 187 with the certainty and perspicuity that we do. This does not mean that this mathematical truth is true for us but not for him.
It means that his ability to perceive truth is limited by factors beyond his control. He can never attain our certainty given the inadequacy of his faculties.
St. Thomas points out that since human beings cannot experientially know immortality in this life, that we do not understand that God is immortal - we merely know that He is not mortal as we are.
This approach is called negative theology and is well described in the first questions of the Summa.