Solid virtue is the state of a soul confirmed in virtue by along practice of good works. The object of this work is to establish us in that happy state in which our will is, as it were, naturally inclined to elicit supernatural acts on all occasions with promptitude, fervour, purity of intention, and perseverance. In the First Part, we will endeavour to remove the obstacles which stand in the way of the practice of solid virtue; in the Second, we will point out the means of acquiring this virtue; and in the Third, we will explain the motives which urge us to perfect ourselves daily in it. The First Part relates to the Purgative Way, the Second to the Illuminative Way, and the Third to the Unitive Way: we will explain and demonstrate the truth of these relations at the conclusion of each of the three Parts. We may reckon six principal obstacles to solid virtue :-venial sin, tepidity, abuse of grace, the predominant passion, human respect, and sloth in rising in the morning. To these six obstacles we win oppose six means of fortifying ourselves in the ways of sanctity:-the perfection of our ordinary actions, meditation, interior recollection, Holy Communion, the particular examen, and a retreat of three days twice a year. Finally, we will also propose six important motives for tending to perfection :-what faith teaches of the excellence of solid virtue, the fear of the evils which befall those who do not practise it, the hope of the blessings of which it is the source, the love of God which demands and merits that we be solidly virtuous, the happiness enjoyed by the perfect, and finally the crown granted to perseverance.