Thales, Heraclitus and Democritus were the Pre-Socratic triumvirate in Greek philosophy. And there were also Anaximander, Anaximenes, Anaxagoras, Empedocles and Leucippus. They all, from Thales to Leucippus, really were scientists.

Pierpaolo Rosati has written:

'Logoi preplatonici' -- subject(s): Ancient Philosophy, Philosophy, Ancient, Pre-Socratic philosophers

The next period after the pre-Socratic philosophers is the Classical period, which includes renowned figures such as Socrates, Plato, and Aristotle. This period marked a shift in philosophical focus towards ethics, epistemology, and metaphysics. Classical philosophy laid the foundations for much of Western philosophy that followed.

The pre-Socratic philosophers were early Greek thinkers before Socrates who laid the foundation for Western philosophy. Some notable pre-Socratic philosophers include Thales, Anaximander, Heraclitus, Parmenides, and Empedocles, who explored metaphysical, cosmological, and ethical questions through their writings and teachings.

Patricia Curd has written:

'A Presocratics reader' -- subject(s): Sources, Ancient Philosophy, Pre-Socratic philosophers