Everyone has at least a passing interest in ancient books of spells, though they aren't always what you would expect after seeing too many witchy movies. Still, the amount of occult knowledge and history you can get from a really old spell book can't be ignored.
If you start to read through any of these books, you'll notice that they are very different from the witchcraft we know of today. Most of these ancient books are based on ceremonial magic, not witchcraft. Witches were fairly private and didn't publish books like these, but ceremonial magicians tended to gather in groups and were much more vocal about sharing their mystical knowledge.
You can order copies of any of these book, just scroll down to the bottom of the page for pics and links.
Well, though I'm sure this is one of the first ancient spell books that comes to mind, I've already discussed this one on another page. Not to mention the fact that it's not an ancient book of spells at all, but a modern book whose idea came from H.P Lovecraft horror fiction. Not only is it recent, it's not filled with real spells at all.
Book of Abramelin the Mage
This book of magic dates to the mid 1300s, and it tells the tale of an Egyptian magician who teaches this system of ceremonial magic to a man named Abraham. The story is written from Abraham's point of view, and he describes the magickal system to his son Lamech. The magic involves elaborate rituals that involve angelic and demonic workings and coded Magic Squares.
The Key of Solomon
Not actually written by King Solomon, this old text was likely compiled in the 14th or 15th centuries. Translations exist in Latin, French and Hebrew as well as a more modern English one. The book is filled with complex rituals with symbols to summon and contain spirits, angels and demons. There are further details on how to work with these spirits to make them do your bidding.
The Black Pullet
Now we have an 18th century grimoire that features spells and rituals that dabble in magick as well as necromancy. The style of magick is mainly the use of talismans, amulets and enchanted rings. The title refers to one specific set of rituals, that will produce the Black Pullet (a chicken that will lay golden eggs), though it is probably referring to a source of wealth rather than an actual chicken. The author of the Black Pullet is unknown, except that he was a soldier in Napoleon's army.
Three Books of Occult Philosophy
This is a set of books written by Heinrich Cornelius Agrippa in the early 1500s, covering 3 aspects of magick: elemental, celestial and intellectual. The books are filled with information on how the many forms of magick relate to each other, and how occult sciences operate. These ancient books of spells are still often used as reference material for witches and magickal practitioners today.