translation.en: Two thousand years ago, Galen, one of the most prominent medical researchers of the ancient world, proposed that while we're awake, our brain's motive force, its juice, would flow out to all the other parts of the body, animating them but leaving the brain all dried up, and he thought that when we sleep, all this moisture that filled the rest of the body would come rushing back, rehydrating the brain
translation.zh: 两千年前 古时候的名医 伽林提出 当我们醒着的时候 我们大脑的原动力，它的液体 会流动到身体所有其他部位 维持它们的活力，但这却使大脑枯竭 并且他认为，在我们睡觉的时候 这些充满了我们身体其他部位的液体 会再回到我们的大脑 为大脑补充水分