Idiom of the week: By heart

Do you ever study by heart? Do you know your friends' phone numbers by heart? 

Confused? No wonder. This idiom is tricky. Strange as it may sound, it has nothing to do with love -not even with liking something.

When you know something by heart, it means you know or have memorized it perfectly. But why is this ability attributed to the heart and not to the brain? Apparently, the ancient Greeks believed that the heart, being the most important organ in the human body, was were intelligence and memory were placed. It was a long time before scientists realized that the heart had nothing to do with the ability to learn or remember -but oh dear! Too late. The idea had already left an imprint on language.