Seeking virtue for its own sake is the height of pride
So on his view it is a very great vice to seek virtue itself for its own sake and to perform the duties of virtue only for the honesty and beauty by which they win our mind's approval and commend themselves to it.
For whoever rises no higher, and does not aim in this at serving God and proving himself to him, holds his own excellence as his highest end and thinks of serving and pleasing himself alone, who is a creature. That is beyond doubt the height of pride and the greatest departure from the true end, and so a very grave sin before God, however much such actions shine in men's eyes.
Those who pursue virtue in this way cannot be excused at all on the ground that virtue by its nature can be referred to God, even though the one who seems to act from virtue does not look to that. For all the other goods of human life, which are never sought for their own sake except viciously, can also be referred to God when considered in themselves.
Latin
XLII. Proinde, juxta ipsum, maxime vitiosum est ipsam virtutem propter se expetere, & virtutis officiis fungi propter solam honestatem atque pulchritudinem, qua se menti nostrae probant & commendant. Qui enim non altius assurgit, nec in eo intendit Deo servire & illi se probare, propriam excellentiam pro summo fine habet, sibique uni, qui creatura est, servire & placere cogitat, quae proculdubio summa superbia est, & maxima a vero fine deviatio, adeoque peccatum coram Deo gravissimum, quantumcunque tales actiones in oculis hominum splendeant. Nec quicquam eo excusari possunt qui virtutem ea ratione sectantur, quod virtus natura sua ad Deum referri possit, licet eo non spectet qui ex virtute agere videtur: cum caetera omnia humanae vitae bona, quae non nisi vitiose propter se expetuntur, ad Deum quoque in se spectata referri possint.