Phosphorus - food for thought

In 1871 the popular American author Mark Twain offered some advice - from the Swiss-born US naturalist Jean Louis Rodolphe Agassiz - to an aspiring author who wanted to know how he might improve his literary skills: 

"Agassiz does recommend authors to eat fish, because the phosphorus in it makes brains. But I cannot help you to a decision about the amount you need to eat. Perhaps a couple of whales would be enough." 

The acerbic witticism inadvertently publicised the link between phosphorus and the brain, and how supplements of the element (either in medicines or found in the diet) might enhance mental powers - a view not without some basis in fact and still popular today, at least in some quarters.