[Alchemists] get a small livelihood by some Physical Experiments, as also by some Paints and effeminate Fucusses [cosmetics], which the Scriptures call the Oyntments of harlott; whence the Proverb, Every Alchymist is a Physician or a Sope-boyler.

[Hermetic philosophy (Alchemy) was the only Art which might be able] to complete and bring to light not only medicine but also a universal Philosophy.
…quaeque sola non Medicinam tantum, sed et universam Philosophiam valde perficere et illustrare possit.

Occult sciences. Those imaginary sciences of the middle ages which related to the influence of supernatural powers, such as alchemy, magic, necromancy, and astrology.

Yet ar ther fibicches in forceres
Of fele raennes makyng,
Experimentz of alkenamye
The peple to deceyve;
If thow thynke to do-wel,
Deel therwith nevere.
There are many men, also, who makes use of strange devices,
Alchemical experiments for the deception of others:
If you desire to do well, have no dealings with these.

Alchemy is the art that separates what is useful from what is not by transforming it into its ultimate matter and essence.

Alchemy. The link between the immemorial magic arts and modern science. Humankind’s first systematic effort to unlock the secrets of matter by reproducible experiment.

Alchymy, or Chymistry, is …
An Art which good men bate, and most men blame,
Which her admirers practice to their shame,
Whose plain Impostures, easie to perceive,
Not onely others, but themselves deceive.

And yet surely to alchemy this right is due, that it may be compared to the husbandman whereof Æsop makes the fable, that when he died he told his sons that he had left unto them gold buried under the ground in his vineyard: and they digged over the ground, gold they found none, but by reason of their stirring and digging the mould about the roots of their vines, they had a great vintage the year following: so assuredly the search and stir to make gold hath brought to light a great number of good and fruitful inventions and experiments, as well for the disclosing of nature as for the use of man's life.

Ars est sine arte, cujus principium est mentiri, medium laborare, et finis mendicare.
The art is devoid of art, whose beginning is falsehood, its middle labour, and its end beggary.
[On the character of the delusive science of alchemy].

Astrology was much in vogue during the middle ages, and became the parent of modern astronomy, as alchemy did of chemistry.

But there is another alchemy, operative and practical, which teaches how to make the noble metals and colours and many other things better and more abundantly by art than they are made in nature. And science of this kind is greater than all those preceding because it produces greater utilities. For not only can it yield wealth and very many other things for the public welfare, but it also teaches how to discover such things as are capable of prolonging human life for much longer periods than can be accomplished by nature … Therefore this science has special utilities of that nature, while nevertheless it confirms theoretical alchemy through its works.

Chemistry is not a primitive science like geometry and astronomy; it is constructed from the debris of a previous scientific formation; a formation half chimerical and half positive, itself found on the treasure slowly amassed by the practical discoveries of metallurgy, medicine, industry and domestic economy. It has to do with alchemy, which pretended to enrich its adepts by teaching them to manufacture gold and silver, to shield them from diseases by the preparation of the panacea, and, finally, to obtain for them perfect felicity by identifying them with the soul of the world and the universal spirit.

Chemistry is one of those branches of human knowledge which has built itself upon methods and instruments by which truth can presumably be determined. It has survived and grown because all its precepts and principles can be re-tested at any time and anywhere. So long as it remained the mysterious alchemy by which a few devotees, by devious and dubious means, presumed to change baser metals into gold, it did not flourish, but when it dealt with the fact that 56 g. of fine iron, when heated with 32 g. of flowers of sulfur, generated extra heat and gave exactly 88 g. of an entirely new substance, then additional steps could be taken by anyone. Scientific research in chemistry, since the birth of the balance and the thermometer, has been a steady growth of test and observation. It has disclosed a finite number of elementary reagents composing an infinite universe, and it is devoted to their inter-reaction for the benefit of mankind.

Chymia, or Alchemy and Spagyrism, is the art of resolving compound bodies into their principles and of combining these again.

Concerning alchemy it is more difficult to discover the actual state of things, in that the historians who specialise in this field seem sometimes to be under the wrath of God themselves; for, like those who write of the Bacon-Shakespeare controversy or on Spanish politics, they seem to become tinctured with the kind of lunacy they set out to describe.

Divers of Hermetic Books have such involv’d Obscuritys that they may justly be compar’d to Riddles written in Cyphers. For after a Man has surmounted the difficulty of decyphering the Words & Terms, he finds a new & greater difficulty to discover ye meaning of the seemingly plain Expression.

I have always looked upon alchemy in natural philosophy to be like enthusiasm in divinity, and to have troubled the world much to the same.

I prefer the spagyric chemical physicians, for they do not consort with loafers or go about gorgeous in satins, silks and velvets, gold rings on their fingers, silver daggers hanging at their sides and white gloves on their hands, but they tend their work at the fire patiently day and night. They do not go promenading, but seek their recreation in the laboratory, wear plain learthern dress and aprons of hide upon which to wipe their hands, thrust their fingers amongst the coals, into dirt and rubbish and not into golden rings. They are sooty and dirty like the smiths and charcoal burners, and hence make little show, make not many words and gossip with their patients, do not highly praise their own remedies, for they well know that the work must praise the master, not the master praise his work. They well know that words and chatter do not help the sick nor cure them... Therefore they let such things alone and busy themselves with working with their fires and learning the steps of alchemy. These are distillation, solution, putrefaction, extraction, calcination, reverberation, sublimination, fixation, separation, reduction, coagulation, tinction, etc.

I submit that the traditional definition of psychiatry, which is still in vogue, places it alongside such things as alchemy and astrology, and commits it to the category of pseudo-science.

Mankind have been slow to believe that order reigns in the universe—that the world is a cosmos and a chaos.
… The divinities of heathen superstition still linger in one form or another in the faith of the ignorant, and even intelligent men shrink from the contemplation of one supreme will acting regularly, not fortuitously, through laws beautiful and simple rather than through a fitful and capricious system of intervention.
... The scientific spirit has cast out the demons, and presented us with nature clothed in her right mind and living under the reign of law. It has given us, for the sorceries of the alchemist, the beautiful laws of chemistry; for the dreams of the astrologer, the sublime truths of astronomy; for the wild visions of cosmogony, the monumental records of geology; for the anarchy of diabolism, the laws of God.

Medicine rests upon four pillars—philosophy, astronomy, alchemy, and ethics. The first pillar is the philosophical knowledge of earth and water; the second, astronomy, supplies its full understanding of that which is of fiery and airy nature; the third is an adequate explanation of the properties of all the four elements—that is to say, of the whole cosmos—and an introduction into the art of their transformations; and finally, the fourth shows the physician those virtues which must stay with him up until his death, and it should support and complete the three other pillars.

On consideration and by the advice of learned men, I thought it improper to unfold the secrets of the art (alchemy) to the vulgar, as few persons are capable of using its mysteries to advantage and without detriment.

Quiet this metal!
Let the manes put off their terror, let
them put off their aqueous bodies with fire.
Let them assume the milk-white bodies of agate.
Let them draw together the bones of the metal.

Rudenesse it selfe she doth refine,
Even like an Alchemist divine,
Grosse times of Iron turning
Into the purest forme of gold:
Not to corrupt, till heaven waxe old,
And be refin'd with burning.

The science of alchemy I like very well. I like it not only for the profits it brings in melting metals, in decocting, preparing, extracting, and distilling herbs, roots; I like it also for the sake of the allegory and secret signification, which is exceedingly fine, touching the resurrection of the dead at the last day.

The tragic element in poetry is like Saturn in alchemy,—the Malevolent, the Destroyer of Nature; but without it no true Aurum Potabile, or Elixir of Life, can be made.

The world hath been much abused by the opinion of making gold; the work itself I judge to be possible; but the means, hitherto propounded, to effect it are, in the practice, full of error and imposture; and in the theory, full of unfound imaginations.

Thus you may multiply each stone 4 times & no more for they will then become oyles shining in ye dark and fit for magicall uses. You may ferment them with ☉ [gold] and [silver], by keeping the stone and metal in fusion together for a day, & then project upon metalls. This is the multiplication of ye stone in vertue. To multiply it in weight ad to it of ye first Gold whether philosophic or vulgar.

We modern chemists, the witnesses and workers of this “Age of Chemistry,” can learn something from the old alchemy, full as it was of errors and fantasies! … Let the Past furnish us a warning against too much phantasy in modern chemistry.

We must examine the moral alchemy through which the in-group readily transmutes virtue into vice and vice into virtue, as the occasion may demand. … We begin with the engagingly simple formula of moral alchemy: the same behavior must be differently evaluated according to the person who exhibits it. For example, the proficient alchemist will at once know that the word “firm” is properly declined as follows:
I am firm,
Thou art obstinate,
He is pig-headed.
There are some, unversed in the skills of this science, who will tell you that one and the same term should be applied to all three instances of identical behavior.

What, then, shall we say about the receipts of alchemy, and about the diversity of its vessels and instruments? These are furnaces, glasses, jars, waters, oils, limes, sulphurs, salts, saltpeters, alums, vitriols, chrysocollae, copper greens, atraments, auripigments, fel vitri, ceruse, red earth, thucia, wax, lutum sapientiae, pounded glass, verdigris, soot, crocus of Mars, soap, crystal, arsenic, antimony, minium, elixir, lazarium, gold leaf salt niter, sal ammoniac, calamine stone, magnesia, bolus armenus, and many other things. Then, again, concerning herbs, roots, seeds, woods, stones, animals, worms, bone dust, snail shells, other shells, and pitch. These and the like, whereof there are some very farfetched in alchemy, are mere incumbrances of work; since even if Sol and Luna [gold and silver] could be made by them they rather hinder and delay than further one’s purpose.