 Theophrastus says that Alcmaeon did not explain sensation by the principle of like to like (i.e. by the likeness between the sense organ and what is perceived), a principle which was used by many early Greek thinkers (e.g., Empedocles). Unfortunately he gives no general account of how Alcmaeon did think sensation worked (DK, A5). Alcmaeon explained each of the individual senses with the exception of touch, but these accounts are fairly rudimentary. He regarded the eye as composed of water and fire and vision as taking place when what is seen is reflected in the gleaming and translucent part of the eye. Hearing arises when an external sound is first transmitted to the outer ear and then picked up by the empty space (kenon) in the inner ear, which transmits it to the brain. Taste occurs through the tongue, which being warm and soft dissolves things with its heat and, because of its loose texture, receives and transmits the sensation. Smell is the simplest of all. It occurs “at the same time as we breathe in, thus bringing the breath to the brain” (DK, A5).