Three friends are walking in the countryside. As they are approaching a big, beautiful apple tree, an apple suddenly falls from a branch to the grassy ground. They stop to look at it and one of them sighs:
“How I would like to know why the apple fell!”
The second friend picks up the apple, takes a bite, and shakes her head in appreciation:
“I’m more impressed by its taste. I want to know why it tastes like that!”
But the third one is already eyeing the tree with interest and adds thoughtfully:
“I am wondering how the apple came from the tree.”
Out of nowhere, a bunch of kids appears and, laughing and running, they cry out: “We want to know how many apples are on this apple tree!” and with lots of pushing and tagging they scramble up its bark, scatter on the branches, and start counting loudly. The friends laugh and then fall in silent contemplation. Each one observes, gropes the ground, the tree, the apple. Every now and then they exchange opinions, ask each other for new ideas, seek validation for their conclusions. Indeed, they all have useful things to say about everything, though, of course, each is more dedicated to their own quest. Occasionally, they look up and ask the kids, which keep on their merry and noisy counting, to confirm their theories.
After some time, they’ve all satisfied their curiosity. The one friend knows why the apple fell. The other has found why it tastes the way it tastes. The last one understands how the apple came to be. And the kids have counted the apples. And after a few more apple-bites under the shadow of the patient apple tree, they all continue their walk. And it’s time I introduced them to you:
The first friend is Physics.
The second is Chemistry.
The third is Biology.
And the kids… are Mathematics!