The ancient Greeks developed basic memory systems called mnemonics. The name is derived from their Goddess of memory "Mnemosyne". In the ancient world, a trained memory was an immense asset, particularly in public life. There were no convenient devices for taking notes, and early Greek orators delivered long speeches with great accuracy because they learned the speeches using mnemonic systems.

　　The Greeks discovered that human memory is largely an associative process that it works by linking things together. For example, think of an apple. The instant your brain registers the word "apple", it recalls the shape, color, taste, smell and texture of that fruit. All these things are associated in your memory with the word "apple". This means that any thought about a certain subject will often bring up more memories that are related to it. An example could be when you think about a lecture you have had. This could trigger a memory about what you're talking about through that lecture, which can then trigger another memory. Associations do not have to be logical. They just have to make a good link. An example given on a website I was looking at follows, "Do you remember the shape of Austria? Canada? Belgium? Or Germany? Probably not. What about Italy though? If you remember the shape of Italy, it is because you have been told at some time that Italy is shaped like a boot. You made an association with something already known, the shape of a boot. And Italy shape could not be forgotten once you had made the association."