We are now in the intellectual level, having risen above the mental level, the Prana level of the vegetable kingdom and the inorganic level. They cannot remember things as we do. We can think of the past and we can think ahead. This is the intellectual level. Understanding alone does not make us happy.
Happiness is a different thing altogether.
The great Reality, the Supreme Being, is said to be constituted of three essences, or constitutive essences we may say, viz. Sat, Chit and Ananda - Existence, Consciousness and Bliss. You can see existence even, in a wall or a brick, but not consciousness. You can see existence and consciousness in a human being where the intellect functions, i.e., when you think, or argue and speak. But you need not be happy at that time.