Friedrich Nietzsche dedicated his book Philosophy in the Tragic Age of the Greeks (1873) to an extremely important part in the history of philosophy: philosophy before Socrates.
In a chapter dedicated to Thales, he offers a great description of the philosophical spirit as contrasted to the scientific spirit.
The philosopher is not a man of intellect, if by stressing intellect one designates a person who can see to the success of his personal undertakings. Aristotle rightly says that “What Thales and Anaxagoras know will be considered unusual, astonishing, difficult and divine, but never useful, for their concern was not with the good. of humanity.” Philosophy is distinguished from science by its selectivity and its discrimination of the unusual, the astonishing, the difficult and the divine, just as it is distinguished from intellectual cleverness by its emphasis on the useless. Science rushes headlong, without selectivity, without “taste,” at whatever is knowable, in the blind desire to know all at any cost. Philosophical thinking, on the other hand, is ever on the scent of those things which are most worth knowing, the great and the important insights. Now the concept of greatness is changeable, in the realm of morality as well as in that of esthetics. And so philosophy starts by legislating greatness. Part of this is a sort of name-giving. “This is a great thing,” says philosophy, thereby elevating man over the blind unrestrained greed of his drive for knowledge. By its concept of greatness philosophy tames this drive, and most of all considering the greatest knowledge of all, the knowledge of the essence and core of all things, as ascertainable and, in fact as certained. When Thales says, “all is water,” man is stung up out of the wormlike probings and creepings about of his separate sciences. He intuits the ultimate resolution of all things and overcomes, by means of such intuition, the vulgar restrictions of the lower levels of knowledge. The philosopher seeks to hear within himself the echoes of the world symphony and to re-project them in the form of concepts. While he is contemplative-perceptive like the artist, compassionate like the religious, a seeker of purposes and causalities like the scientist, even while he feels himself swelling into a macrocosm, he all the while retains a certain self-possession, a way of viewing himself coldly as a mirror of the world. This is the same sense of self-possession which characterizes the dramatic artist who transforms himself into alien bodies and talks with their alien tongues and yet can project this transformation into written verse that exists in the outside world on its own. What verse is for the poet, dialectical thinking is for the philosopher. He grasps for it in order to get hold of his own enchantment, in order to perpetuate it. And just as for the dramatist words and verse are but the stammering of an alien tongue, needed to tell what he has seen and lived, what he could utter directly only through music or gesture, just so every profound philosophic intuition expressed through dialectic and through scientific reflection is the only means for the philosopher to communicate what he has seen. But it is a sad means; basically a metaphoric and entirely unfaithful translation into a totally different sphere and speech. Thus Thales had seen the unity of all that is, but when he went to communicate it, he found himself talking about water!