The eighth sentence is rendered in many alchemical books as follows: "Ascend with the greatest sagacity from the earth to heaven, and then again descend to the earth, and unite together the powers of things superior and things inferior.

Thus you will obtain the glory of the whole world, and obscurity will fly away from you." This sentence evidently teaches the unity of things in heaven and things on earth, and asserts the possibility of gaining, not merely a theoretical, but also a practical, knowledge of the essential characters of all things.

Moreover, the sentence implies that this fruitful knowledge is to be obtained by examining nature, using as guide the fundamental similarity supposed to exist between things above and things beneath.
The alchemical writers constantly harp on this theme: follow nature; provided you never lose the clue, which is simplicity and similarity.
The author of _The Only Way_ (1677) beseeches his readers "to enlist under the standard of that method which proceeds in strict obedience to the teaching of nature ...

in short, the method which nature herself pursues in the bowels of the earth." The alchemists tell us not to expect much help from books and written directions.

When one of them has said all he can say, he adds--"The question is whether even this book will convey any information to one before whom the writings of the Sages and the open book of Nature are exhibited in vain." Another tells his readers the only thing for them is "to beseech God to give you the real philosophical temper, and to open your eyes to the facts of nature; thus alone will you reach the coveted goal." "Follow nature" is sound advice.