Aristotle was a Classic Empiricist of the greek tradition, so, if one wants to get a quick glance at Classic Empiricism before Locke and Hume, read on:
Universal Concepts Being Established in the Intellect- Aristotle
Aristotle, known for his development of classical empiricism, once drew an analogy between the process of universal concepts(as opposed to platonic pure forms) being internalised by the mind and a company of soldiers retreating.
As they leave, in great disorder, they try to form a united company again, but have a great bit of difficulty doing so. What changes this is one soldier halting(an individual experience irrelevant of a platonic Form) and making a stand. Then another sees him, and does the same( a second experience reinforcing the creation of a universal concept ) and then a third, etc., etc., until a generalisation is created, and the company is in formation again, and ready for battle.
This offers the reader an easy way to visualise Aristotle's concept of empirical concept-forming. Human beings, he thought, derived their universal ideas from experience, and then these would become the tools, brick and mortar of all reasoning and intellect.