In between painting the Mona Lisa and idly designing flying machines for fun, Leonardo Da Vinci occasionally got outside and looked up every now and again. Because he was Da Vinci, the moment he did, he discovered a new natural law. This one was about trees, and after five hundred years, scientists are still trying to figure out why the law worked in the first place.

Strip the leaves off of the average tree, soak the whole thing in water until it gets mushy, bundle the branches up together, and you'll get what looks like one long trunk. That's what Leonardo Da Vinci said in the fifteen hundreds. If a tree trunk splits off into three main branches, each of the branches will be one third the size of the trunk. When each of those branches splits into three again, making nine branches on the second 'tier' of the tree, each of these second tier branches will be one ninth the side of the trunk. As the branches grow and split, they will always be a particular fraction of the size of the trunk, and adding together all the fractional bits of each 'tier' of branches will always add up to 'one trunk.' This isn't the case in all trees, but the majority hold to this pattern.

The reason for this, to me, is obvious: Trees love fractions. They're like third grade teachers that way. (They're also like third grade teachers in that they don't like it when kids play with matches, but that was probably the subject of a separate Da Vinci observation.)