"The strongest arguments prove nothing so long as the conclusions are not verified by experience."

"The study of alchemy is not only useful, but necessary, for the perfection of all other sciences."

"The world is full of errors, and men are in darkness, and they do not know it."

"The present state of philosophy is deplorable, and needs to be reformed."

"It is necessary to know the causes of things, and not only their effects, if we wish to have perfect knowledge."