We are told that Herophilus, who was considered one of the greatest doctors, said that medicines are the hands of the gods. In my opinion, he was quite right, since drugs that have been tried and tested can indeed achieve the same result as divine intervention (Scribonius Largus, Prescriptions Preface).
Nature intended that our only medicines should be those which are widely available, easy to find, and cost nothing, derived from the same sources as the food on which we live. But later on human deceit devised those dreadful laboratories which promise each of us a way to prolong our lives, provided we are willing to pay for it. All at once people are singing the praises of highly elaborate compounds and mixtures, cures from Arabia and India are at a premium, a medication for some slight sore is imported from the Red Sea – even though the very poorest among us dines every day on foods that really should be the source of our medications. But if remedies were sought from the herbs and shrubs that grow in our own gardens, no art would be less highly regarded than medicine (Pliny, Natural History 24.4).
The reason why there is so little research into the medicinal properties of various herbs is that only illiterate country folk who live surrounded by them make use of them; faced with hordes of doctors, the rest of us do not trouble to look for herbal remedies (Pliny, Natural History 25.16).
Peonies counteract the night-time delusions inflicted on us by woodland spirits. It is recommended that they should be dug up at night, since the woodpecker sacred to Mars would attack the eyes of anyone it saw gathering them in the daytime (Pliny, Natural History 25.29).
Laserpicium, which the Greeks call “silphion” and which was discovered in Cyrenaica, is a very famous plant. Its juice, known as “laser”, has very important medicinal and other applications, and costs the same by weight as silver. But it is many years now since it was last found in Cyrenaica, since the tax officials who have taken a lease on the pastures have been overgrazing them with cattle, which they regard as more profitable. Within living memory, only one single stalk of silphium has ever been discovered there, and it was sent as a gift to the emperor Nero (Pliny, Natural History 19.38).
The governor of Egypt sentenced some convicted criminals to be thrown to ravening wild beasts to be eaten. As they were going into the theater designated for the punishment of thieves, a woman selling things by the roadside took pity on them and gave them some of the citron she was eating. They took it and ate it, and very soon after were thrown to the asps, monstrous and savage creatures. The asps bit them, but they were not harmed at all. The governor was baffled. Eventually he asked the soldier who was guarding the criminals whether they had eaten or drunk anything. When he learned that they had been given pieces of citron, the next day he ordered one criminal to be given a piece of citron, but not the other. The one who ate it suffered no harm when he was bitten, but the other died as soon as he was bitten. Since many further experiments produced the same result, the citron was proved to be an antidote to all deadly drugs (Athenaeus, Wise Men at Dinner 3.28).
I am not going to discuss medicines made with ingredients brought here for sale from India, or Arabia, or any other foreign part of the world. Substances produced so far away do not suit our remedies; they do not grow for us, in fact they do not even grow for the native population there either, or they would not be selling them on to people elsewhere. … I intend to demonstrate that it is possible to maintain good health without such stuff, and I shall do so even if it is only to put those people to shame who indulge in the modern decadent way of life (Pliny, Natural History 22.118).
It is important to devote time to personal examination of each medicine, so as to distinguish those that are effective from those that are useless. For drug sellers are so crafty at tampering with medicines that they can fool even people with great experience in such matters (Galen, On Antidotes 14.7K).