Josef Pieper explores these questions by explaining and defending St. Thomas' doctrine that contemplation is the deepest happiness of Man.
"Contemplation is man's greatest happiness" is a concept completely foreign to contemporary American society. It requires a fair amount of exploration and explanation just to understand what the statement is actually asserting. Because we tend to focus so strongly on action, and view contemplation as "doing nothing," we are very apt to completely miss St. Thomas' point.
To contemplate is, at the deepest level, to see something as it truly is. It is not just seeing the external characteristics of an object, but in a sense it is "seeing through" the object to the Love and Joy of the Creator of the Universe. To contemplate is to dwell in the reality of things.
My description falls far short of providing any real clarity. For that, I refer you to Josef pipers book. It is short and accessible and rewards a careful reading.
Some choice quotes:
Quoting Augustine: "No matter how much you labor, you labor to this end: that you may see."
"...everything holds and conceals at bottom a mark of its divine origin; that one who catches a glimpse of it 'sees' that this and all things are 'good' beyond all comprehension; and that, seeing this, he is happy. Here in sum is the whole doctrine of the contemplation of earthly creation." [pg. 88]
"This, incidentally, may suggest that the greatest menace to our capacity for contemplation is the incessant fabrication of tawdry empty stimuli which kill the receptivity of the soul..." [pg. 102]