Faith principles need the Spirit's illumination — unlike science axioms
Theologians commonly mark this difference between the principles of faith and the principles of the sciences. Science axioms are known in themselves, evident, and by their own light compel assent from natural reason. Faith principles do not have that same evidence. So, as is right, they cannot be believed and received except through the Holy Spirit's inward illumination.
Yet they agree in this: we assent to natural principles at once by the mind's natural light, not through other better-known principles that prove them. In the same way we believe faith's principles immediately through the Spirit's illumination — not by some intervening proof drawn from other principles more known in that order.
Latin
XVII. Ex communi quidem Theologorum sensu, in eo discrimen est inter principia fidei, & principia scientiarum, quod principia scientiarum per se nota sunt, & evidentia, & sua luce assensum extorquent a naturali rationis lumine: principia vero fidei non habent parem evidentiam; ideoque, sicuti par est, credi & suscipi non possunt, nisi per illuminationem internam Spiritus sancti. Attamen in hoc conveniunt, quod sicuti principiis naturalibus assentimur immediate per naturale lumen intellectus, non vero per alia notiora quaedam principia, per quae demonstrata fuerint; ita quoque fidei principiis credimus immediate, per Spiritus sancti illuminationem, non vero interventu probationis alicujus, quae ducta sit ex aliis notioribus in hoc genere principiis.