Full Idea
The point of our investigation is to acquire knowledge, and a prerequisite for knowing [eidenai] anything is understanding why it is as it is - in other words, grasping its primary cause.
Gist of Idea
To know something we need understanding, which is grasp of the primary cause
Source
Aristotle (Physics [c.337 BCE], 194b18)
Book Reference
Aristotle: 'Physics', ed/tr. Waterfield,Robin [OUP 1996], p.38
A Reaction
He then proceeds to identify four types of cause (Idea 8332). I can't think of a better account of knowledge. If we want to know that cigarettes cause cancer, we must get beyond the statistical correlation, and grasp the physical mechanisms.
Related Ideas
Idea 8332 The four causes are the material, the form, the source, and the end [Aristotle]
Idea 543 All men long to understand, as shown by their delight in the senses [Aristotle]
Idea 12038 Translate as 'humans all desire by nature to understand' (not as 'to know') [Aristotle, by Annas]