- The sun is invisible in men, but visible in the world, yet both are of one and the same sun.
- Theatrum Chemicum Volume 1 Spec. phil.
- It is the study of the Chemists to liberate that unsensual truth from its fetters in things of sense, for through it the heavenly powers are persued with subtle understanding....Knowledge is the sure and undoubted resolution by experiment of all opinions concerning the truth....Experiment is manifest demonstration of the truth, and resolution the putting away of doubt. We cannot be resolved of any doubt save by experiment, and therefore is no better way to make it than on ourselves. Let us therefore verify what we have said above concerning the truth, beginning with ourselves. We have said that piety consists in knowledge of ourselves, and hence it is said that we make philosophical knowledge begin from this also. But no man can know himself unless he know what and not who he is, on whom he depends and whose he is (for by the law of truth no one belongs to himself, and to what end he was made. With this knowledge piety begins, which is concerned with two things, namely, with the Creator and the creature that is made like unto him. For it is impossible for the creature to know himself of himself, unless he first know his Creator....No one can better know the Creator, than the workman is known by his work.
- Theatrum Chemicum Volume 1 phil. med.