There are in fact two things, science and opinion. The former begets knowledge, the latter ignorance.
Science begets knowledge; opinion, ignorance.
Through seven figures come sensations for a man; there is hearing for sounds, sight for the visible, nostril for smell, tongue for pleasant or unpleasant tastes, mouth for speech, body for touch, passages outwards and inwards for hot or cold breath. Through these come knowledge or lack of it.
I also maintain that clear knowledge of natural science must be acquired, in the first instance, through mastery of medicine alone.