Thomas Aquinas

“ He that is prone to yield to his passions on account of his impulse to action is simply more apt for the active life by reason of his restless spirit. Hence Gregory says (Moral. vi, 37) that "there be some so restless that when they are free from labor they labor all the more, because the more leisure they have for thought, the worse interior turmoil they have to bear." Others, on the contrary, have the mind naturally pure and restful, so that they are apt for contemplation, and if they were to apply themselves wholly to action, this would be detrimental to them. ”

“ In this way they will known when they withdraw within themselves, in order to explore spiritual things, whether they no longer carry with them the shadows of the things corporeal, or, if these follow them, whether they prudently drive them away." Hence the work of the active life conduces to the contemplative, by quelling the interior passions which give rise to the phantasms whereby contemplation is hindered. ”

“ Without the contemplative life it is possible to enter the heavenly kingdom, provided one omit not the good actions we are able to do; but we cannot enter therein without the active life, if we neglect to do the good we can do. ”

“ External labor conduces to the increase of the accidental reward; but the increase of merit with regard to the essential reward consists chiefly in charity, whereof external labor borne for Christ's sake is a sign. Yet a much more expressive sign thereof is shown when a man, renouncing whatsoever pertains to this life, delights to occupy himself entirely with Divine contemplation.
Reply to Objection 2: In the state of future happiness man has arrived at perfection, wherefore there is no room for advancement by merit ”

“ Our Lord adds a ninth reason (Lk. 10:42) when He says: "Mary hath chosen the best part, which shall not be taken away from her," which words Augustine (De Verb. Dom. Serm. ciii) expounds thus: "Not---Thou hast chosen badly but---She has chosen better. Why better? Listen---because it shall not be taken away from her. But the burden of necessity shall at length be taken from thee: whereas the sweetness of truth is eternal." ”