After the time of St. Thomas moral theology often followed the order of the Decalogue, of which many precepts are negative. The saint himself follows the order of the virtues, theological and moral, showing their subordination and interconnections. These virtues he sees as functions of one and the same spiritual organism, functions supported by the seven gifts which are inseparable from charity. Thus moral theology is primarily a science of virtues to be practiced, and only secondarily of vices to be shunned. It is something much higher than casuistry, which is mere application to cases of conscience.
Reginald Garrigou-Lagrange, Reality 47