Nine Books on the Nature of Things

If in some places you do not sufficiently understand what I mean, and want a fuller explanation of one or more procedures, write to me privately. I shall explain the matter more clearly and give you sufficient instruction and understanding. Yet I believe this will be unnecessary, and that you will understand well enough without it, since I know how richly God has endowed you with skill in the arts and good judgement. Besides, you know my disposition and meaning; you will therefore understand me readily and easily. I fully hope, and do not doubt, that you will value the present work and cherish what has been entrusted to you, as it deserves. You will not publish it at all, but keep it a close secret for yourself and your family. It is indeed a hidden and great treasure, a noble jewel and a precious thing, which must not be thrown before swine—that is, sophists and people who despise all good natural arts and secrets. Such people do not deserve even to read them, much less to possess, know and understand them. Though this little book is very small and contains few, brief words, it is full of many great arcana. I shall write here from practice, from the light of nature and experience itself, rather than from speculation or theory; I shall not burden or weary you with many words, and so on.