What were the principal contributions of the naturalistic and humanistic philosophers?

What will be an ideal response?

During the sixth century B.C.E., a small group of Greek thinkers introduced methods of intellectual inquiry that combined careful observation, systematic analysis, and the exercise of pure reason. These individuals, whom we call philosophers (literally, "lovers of wisdom"), laid the foundations for Western science and philosophy.
The Naturalists reasoned that there must be a single unifying substance that formed the basic "stuff" of nature. They asked, "What is everything made of?" "How do things come into existence?" and "What permanent substance lies behind the world of appearance?" Leucippus of Miletus theorized that physical reality consisted of minute, invisible particles that moved ceaselessly in the void. These he called atoms, the Greek word meaning "indivisible." Democritus, a follower of Leucippus and the best known of the naturalist philosophers, developed the atomic theory of matter. According to this materialist view, atoms moved constantly and eternally according to chance in infinite time and space. The atomic theory survived into Roman times, and, although forgotten for 2,000 years thereafter, it was validated by physicists of the early twentieth century. Pythagoras, the founding father of pure mathematics, believed that proportion, discovered through number, was the true basis of reality.
The Humanists turned their attention from the world of nature to the realm of the mind, from physical matters to moral concerns, and from the gathering of information to the cultivation of wisdom. Athens' foremost Humanist philosopher, Socrates, insisted on the absolute nature of truth and justice, describing the ethical life as belonging to a larger set of universal truths and an unchanging moral order. For Socrates, virtue was a condition of the psyche, the seat of both the moral and intellectual faculties of the individual. Hence, understanding the true meaning of virtue was preliminary to acting virtuously: to know good is to do good. His pupil, Plato, believed there was a higher reality of eternal truths, which he called Forms, and was distinct from the imperfect and transient objects of sensory experience, which were mere copies of Forms. Plato's Theory of Forms proposes that all sensory objects are imitations of the Forms, which, like the simplest mathematical equations, are imperishable and forever true.