Two ways of keeping the precepts: as to the substance of the work, and as ordered to salvation
The precepts of that law can be kept in two ways: first, only as to the substance of the works; second, in the manner by which they are ordered to eternal salvation and the blessedness promised to us.
A man keeps a precept as to the substance of the work when he freely refrains from what a precept forbids, such as theft or murder, or freely does what the law commands, such as honouring a parent, caring for his own family, or helping the needy from his own means.
For such works to profit us toward eternal salvation, more is needed: they must be done out of charity, from the love of God that the Gospel commends, and directed to God's glory. So to keep the precepts in this second way is not only to do the work the law commands, outward or inward, but also to do it out of charity.
Latin
V. Porro legis istius praecepta duplici modo observari possunt. Primo duntaxat secundum operum substantiam. Secundo quoad modum quo ordinantur ad salutem aeternam & beatitudinem nobis promissam. Quoad operis substantiam praeceptum legis servat, qui voluntarie abstinet ab eo quod aliquo legis praecepto prohibetur, verbi causa, a furto, & ab homicidio, & qui voluntarie praestat aliquid quod lege jubetur, ut est honorem parenti exhibere, curam gerere suorum, & egenti de suo subvenire. Sed ut ista nobis prosint ad salutem aeternam, requiritur praeterea ut fiant ex charitate, & ex illo Dei amore quem commendat Evangelium, ac ut ad Dei gloriam dirigantur. Adeoque legis praecepta servare posteriori isto modo, est non solum opus quod lege praecipitur, sive externum sit, sive internum etiam, praestare, sed praeterea istud ex charitate facere.