Works not referred to God serve the creature, not the Creator
In the previous chapter he proves at length that all love of the world and of the creature is vicious, that is, when any creature is loved for its own sake and not for God. From this he gathers that all works not referred to God, to be possessed in eternal life, are bad by the very fact that in them men love the world, not God. So they serve the creature, not the Creator, and obey concupiscence, or cupidity, which the devil planted in man, not charity, which God planted.
'For,' he says, 'no middle can be imagined between the Creator and the creature, between the world and God, for them to pursue in acting; nor any middle way between cupidity and charity by which they are moved in their morally good actions. Only an ungodly man would deny that it is a sin to serve the creature by cupidity rather than the Creator, and to love the world rather than God while acting.
So in those works, however good and philosophical, and however free of sin they may seem, if they are done without faith in God, a Christian may not doubt that those who lack the faith that directs the intention serve the creature, not the Creator; for it is impossible that in acting they serve no one. A man serves whatever he looks to and loves as the end of his work, whether that is his work itself, or the object of the work, or (which is always so, and does not exclude the other two) the very man who seems to be doing a morally good work.
For by the very fact that in acting he looks either to the empty splendour of the work, as the Stoics did, or to honour, riches, pleasure or his own curiosity, as other philosophers did, he seeks for himself whatever he regards as final, not for God, whom he does not know at all. So no evasion can excuse him: in that very work he serves the creature, not the Creator.'
Latin
XLI. Et capite praecedenti prolixe probat vitiosum esse omnem amorem mundi & creaturae, quum scilicet, creatura quaevis amatur propter se & non propter Deum. Unde colligit omnia opera, quae non referuntur ad Deum in aeterna vita possidendum, hoc ipso mala esse, quod in iis homines mundum, non Deum, diligunt: adeoque creaturae serviunt non Creatori, & concupiscentiae, seu cupiditati obediunt, quam Diabolus in homine plantavit, non charitati, quam Deus. Nec enim, inquit, inter Creatorem & creaturam, inter mundum & Deum, aliquid medium fingi potest, quod operando sectentur: vel inter cupiditatem & charitatem medius modus, quo in suis actionibus moraliter bonis impellantur. Creaturae vero cupiditate servire, potius quam Creatori, mundum inter operandum diligere, non Deum, solus impius negaverit esse peccatum. In operibus igitur illis, quantumcunque bona, & Philosophica, & sine peccato facta videantur, si sine Dei fide fiant, non sinitur dubitare Christianus, eos qui fide intentionem dirigente carent, servire creaturae, non Creatori: impossibile est enim quin alicui operando serviant. Illi quippe servit homo quod ut finem operis sui intuetur, ac diligit, sive sit ipsum opus ejus, sive objectum operis, sive (quod perpetuum est, nec excludit illa duo praecedentia) ipsemet qui opus moraliter bonum videtur operari. Hoc ipso enim quo vel vanum illum splendorem operis, ut Stoici, vel honorem, vel divitias, vel voluptatem, vel curiositatem suam operando spectat, ut alii Philosophi spectaverunt, sibi utique quicquid ut ultimum spectat appetit, non vero Deo, quem penitus nescit: atque ita nulla tergiversatione excusari potest, quin creaturae in ipso opere serviat, non Creatori.