THE brain is a muscle: and like all our other muscles, it needs exercising to stay in shape.
But how? Think memory.
Memory Craft, by Lynne Kelly, introduces the best memory techniques humans have ever devised - from ancient times and the Middle Ages, to methods used by today's memory athletes.
Kelly has tested all these methods in experiments which demonstrate the extraordinary capacity of our brains at any age.
There are simple strategies for anyone who has trouble remembering names or dates, and for older people who want to keep their mind agile.
Above all, Kelly says memorising things can be playful, creative and great fun.
And it doesn't have to be all that complicated. Basically, try memorising anything... from a shopping list to a speech, perhaps using a visual alphabet in which you make some kind of link between what you want to remember and the object.
"Once your visual alphabet is established, which doesn't take long, you can use it forever," Kelly writes.
"You will find that recall from your memory is much faster than constantly finding your place on a written list."
Kelly says we have much to learn from the way ancient indigenous cultures "memorised all the knowledge on which their survival, physically and culturally, depended".
Did you know the American Navajo had classified more than 700 insects, and the Hanunoo in the Philippines classified 1625 plants - all in memory.
And the Matses peoples of Brazil and Peru have recorded their traditional medicine in a 500-page encyclopaedia - yes, from memory!
So what about age? While Kelly agrees memory loss in old age is very common, she says it is not inevitable.
Perhaps we're relying more on Mr Google to glean facts than challenging our memories to recall them. Surely using our brains less can't be helpful.
Memory Craft, by Lynne Kelly (Allen & Unwin) RRP $32.99.
Dr Lynne Kelly is the memory whisperer, a senior memory champion, science writer and honorary research associate at La Trobe University Melbourne. She is also author of groundbreaking book The Memory Code.