"On the saying of Gregory, 'Often they who might have contemplated God in peace and quiet, have fallen and given way under the burden of occupations; and others who, had they had occupation, would have lived well and profitably to mankind, have perished under the sword of their own peace and quiet,' -- it is to be remarked that persons of strong passionate inclinations, which tempt them to impetuous actions, are, absolutely speaking, better fitted for an active life, owing to the restlessness of their Spirit. Hence Gregory Says: 'Some are so restless that if they get rest from labour, they labour all the more grievously, because the more liberty and free time they have for their own thoughts, the worse storms they endure in their hearts.' Others again have naturally a purity and peace of soul fitting them for contemplation; and if these persons are totally set aside for active occupations, they will suffer loss (Sum. Theol. 2a-2ae, q. 182, art. 4: Aquinas Ethicus, II, 390).
Of God and His Creatures: 3.134