Grace moves the will without prejudice to its freedom
Thesis XLI. Likewise, in the Protestants' mind, the presence and efficacy of grace, when it is at work, does no harm at all to human freedom. Actions done with grace moving and helping are no less free than they would be if they were supposed done without grace.
Grace does no violence to the human will; it moves it in a way suited to a free faculty, with a deliberate judgement of the mind going before and accompanying the act, and without taking from the will the power to act otherwise. So all good works are effects of divine grace in such a way that they are also acts of a free choice set free by grace, which acts not by its own powers but by those grace has supplied.
Latin
XLI. Similiter gratiae cum adest praesentia atque efficacia, ex Protestantium mente, nihil omnino praejudicat humanae libertati. Neque minus liberae sunt actiones quae gratia movente & auxiliante fiunt, quam si absque gratia fieri supponantur. Nec enim gratia vim ullam humanae voluntati affert, sed eam movet liberae facultati congruenter, nimirum praeeunte & interveniente deliberato mentis judicio, & sic ut a voluntate non tollat aliter agendi potestatem. Adeoque bona quaelibet opera, ita sunt effecta gratiae divinae, ut sint etiam actus liberi arbitrii a gratia liberati, & agentis non ex propriis viribus, sed ex illis quas ipsi gratia suppeditavit.