The following article is taken from the book Uncle John's Legendary Lost Bathroom Reader.
Today we know that there's no such thing as unicorns. But back in the 1500s, they were sort of a respectable version of Bigfoot. Although only a few people had ever "seen" them, it was widely believed that they existed. So when Topsell's Historie of Four Foot Beasties, the first illustrated natural history in English, was published in 1607, unicorns were included. Here are some excerpts from the original version of the book. Remember, as you read, that these descriptions were considered science, not fantasy.
ABOUT THE HORN
* "We will now relate the true history of the horn of the unicorn. The horn grows out of the forehead between the eyelids. It is neither light nor hollow, nor yet smooth like other horns, but hard as iron, rough as a file. It is wreathed about with divers spires. It is sharper than any dart, and it is straight and not crooked, and everywhere black except at the point."
* "The horn of the unicorn has a wonderful power of dissolving and expelling all venom or poison. If a unicorn puts his horn into water from which any venomous beast has drunk, the horn drives away poison, so that the unicorn can drink without harm. It is said that the horn being put on the tables of kings and set among their junkets and banquets reveals any venom if there be any such therein, by a certain sweat which comes over the horn."
* "The horn of a unicorn being beaten and boiled in wine has a wonderful effect in making the teeth white or clear. And thus much shall suffice for the medicines and virtues arising from the unicorn."
THE WILD CREATURE
* "Unicorns are very swift. They keep for the most part in the deserts and live solitary in the tops of mountains. There is nothing more horrible than the voice or braying of the unicorn, for his voice is strained above measure."
* "The unicorn fights with both the mouth and his heels, with the mouth biting like a lion's and the heels kicking like a horse's. He is a beast of untamable nature. He fears not iron nor any iron instrument."

* "What is most strange of all other is that he fights with his own kind (yea, even with females unto death, except when he burns in lust for procreation), but unto stranger-beasts, with whom he has no affinity in nature, he is more sociable and familiar, delighting in their company when they come willingly unto him, never rising against them, but proud of their dependence and retinue, keeps with them all quarters of leagues and truce."