Do we all know?

A thing may be known in two ways: first, in itself; secondly, in its effect, wherein some likeness of that thing is found: thus someone not seeing the sun in its substance, may know it by its rays. So then no one can know the eternal law, as it is in itself, except the blessed who see God in His Essence. But every rational creature knows it in its reflection, greater or less. For every knowledge of truth is a kind of reflection and participation of the eternal law, which is the unchangeable truth, as Augustine says (De Vera Relig. xxxi). Now all men know the truth to a certain extent, at least as to the common principles of the natural law: and as to the others, they partake of the knowledge of truth, some more, some less; and in this respect are more or less cognizant of the eternal law.