History1

By convention there is color,
By convention sweetness,
By convention bitterness,
But in reality there are atoms and space.

Socrates: So they are, my boy, quite without culture. But others are more clever, whose secret doctrines I am going to disclose to you. For them the beginning, upon which all the things we were just now speaking of depend, is the assumption that everything is real motion and that there is

qualities which also can be wholly expressed mathematically. The reality of the universe is geometrical; the only ultimate characteristics of nature are those in terms of which certain mathematical knowledge becomes possible. All other qualities, and these are often far more prominent to the senses, are secondary, subordinate effects of the primary.

Of the utmost moment was Galileo's further assertion that these secondary qualities are subjective. In Kepler there had been no clear statement of this position; apparently for him the secondary qualities were out there in the astronomical world, like the primary, only they were not so real or fundamental.

It was extraordinarily difficult for even the most brilliant of Newton's contemporaries to accept his doctrine that light existed in an infinite number of different independent colors, incapable of being changed into each other, and characterised by a different refrangibility. He seemed to be refuted by experiments in which a mixture of paints of two colours produced paint of a third color, and by other experiments belonging to the subjective physiological theory of color-vision, in which colors really are compounded out of primaries.

Whittaker

Be a philosopher; but, amidst all your philosophy, be still a man.

	History teaches us 1: Democritus, Plato, Galileo, Newton, Locke, Descartes, Hume
Democritus	I wish to demonstrate in a little more detail the very strange state of affairs already noticed in a famous fragment of Democritus of Abdera the strange fact that on the one hand all our knowledge of the world around us, both that gained in everyday life and that revealed by the most painstaking laboratory experiments, rests entirely on immediate sense perception, while on the other hand this knowledge fails to reveal the relations of the sense perceptions to the outside world, so that in the picture or model that we form of the outside world, guided by our scientific discoveries, all sensual qualities are absent. If you ask a physicist what is his idea of yellow light, he will tell you that it is transversal electro- magnetic waves of wavelength in the neighborhood of 590 millimicrons. If you ask him: But where does yellow come in? he will say: In my picture not at all, but these kinds of vibrations, when they hit the retina of a healthy eye, give the person whose eye it is the sensation of yellow. Schrödinger	Democritus I would rather discover a single causal connection than win the throne of Persia. By convention there is color, By convention sweetness, By convention bitterness, But in reality there are atoms and space.
Plato	Plato Socrates: So they are, my boy, quite without culture. But others are more clever, whose secret doctrines I am going to disclose to you. For them the beginning, upon which all the things we were just now speaking of depend, is the assumption that everything is real motion and that there is	nothing besides this, but that there are two kinds of motion, each infinite in the number of its manifestations, and of these kinds one has an active, the other a passive force. From the union and friction of these two are born offspring, infinite in number, but always twins, the object of sense and the sense which is always born and brought forth together with the object of sense. Now we give the senses names like these: sight and hearing and smell, and the sense of cold and of heat, and pleasures and pains and desires and fears and so forth. Those that have names are very numerous, and those that are unnamed are innumerable. Now the class of objects of sense is akin to each of these; all sorts of colors are akin to all sorts of acts of vision, and in the same way sounds to acts of hearing, and the other objects of sense spring forth akin to the other senses. What does this tale mean for us, Theaetetus, with reference to what was said before? Do you see? Plato
Galileo	Hence I think that these tastes, odours, colours, etc., on the side of the object in which they seem to exist, are nothing else than mere names, but hold their residence solely in the sensitive body [...] Swept on by the inherent necessities of this mathematical metaphysic, Galileo, like Kepler, was inevitably led to the doctrine of primary and secondary qualities, only with the Italian genius the doctrine appears in a much more pronounced and developed form. Galileo makes the clear distinction between that in the world which is absolute, objective, immutable, and mathematical; and that which is relative, subjective, fluctuating, and sensible. [...] The Copernican astronomy and the achievements of the two new sciences must break us of the natural assumption that sensed objects are the real or mathematical objects. They betray certain qualities, which, handled by mathematical rules, lead us to a knowledge of the true object, and these are the real or primary qualities, such as number, figure, magnitude, position and motion [...]	Galileo In questions of science the authority of a thousand is not worth the humble reasoning of a single individual. qualities which also can be wholly expressed mathematically. The reality of the universe is geometrical; the only ultimate characteristics of nature are those in terms of which certain mathematical knowledge becomes possible. All other qualities, and these are often far more prominent to the senses, are secondary, subordinate effects of the primary. Of the utmost moment was Galileo's further assertion that these secondary qualities are subjective. In Kepler there had been no clear statement of this position; apparently for him the secondary qualities were out there in the astronomical world, like the primary, only they were not so real or fundamental. Burtt
Descartes	Then, as regards body in particular, we have only the notion of extension, which entails the notions of shape and motion; and as regards the soul on its own, we have only the notion of thought, which includes the perceptions of the intellect and the inclinations of the will . § Then, as regards body in particular, we have only the notion of extension, which entails the notions of shape and motion; and as regards the soul on its own, we have only the notion of thought, which includes the perceptions of the intellect and the inclinations of the will...	Descartes The reading of all good books is like a conversation with the finest minds of past centuries.
Newton	Newton Truth is ever to be found in the simplicity, and not in the multiplicity and confusion of things. the science of colours becomes a speculation as truly mathematical as any other part of physics.	For the Rays (of light) to speak properly are not colored. In them there is nothing else than a certain Power and Disposition to stir up a Sensation of this or that Color. [...] in the Rays they are nothing but their Dispositions to propogate this or that Motion into the Sensorium, and in the Sensorium they are Sensations of those Motions under the form of Colors.
	It was extraordinarily difficult for even the most brilliant of Newton's contemporaries to accept his doctrine that light existed in an infinite number of different independent colors, incapable of being changed into each other, and characterised by a different refrangibility. He seemed to be refuted by experiments in which a mixture of paints of two colours produced paint of a third color, and by other experiments belonging to the subjective physiological theory of color-vision, in which colors really are compounded out of primaries. Whittaker
Locke	These I call original or primary qualities of the body, which I think we may observe to produce simple ideas in us, viz., solidity, extension, figure, motion or rest, and number. Secondly, such qualities which in truth are nothing in the objects themselves, but powers to produce various sensations in us by their primary qualities, i.e. by the bulk, figure, texture, and motion of their insensible parts, as colour, sounds, tastes, etc., these I call secondary qualities. The ideas [perceptions] of primary qualities of bodies are resemblances of them, [i.e., of qualities of matter] and their patters do really exist in the bodies themselves; but the ideas produced in us by these secondary qualities have no resemblance of them at all. [...] What is sweet, blue or warm in idea, is but bulk, figure, and motion of the insensible parts in the bodies themselves, which we call so ... A piece of manna of a sensible bulk, is able to produce in us the idea of a round or square figure; and by being removed from one place to another, the idea of motion. This idea of motion represents it, as it really is in the manna moving; a circle or square are the same, whether in idea or existence; in the mind or in the manna.	Locke Education begins the gentleman, but reading, good company and reflection must finish him. No man's knowledge here can go beyond his experience. And this, both motion and figure are really in the manna, whether we take notice of them or not. This everybody agrees to. Besides, manna by the bulk, figure, texture and motion of its parts has a power to produce the sensation of sickness, or sometimes of acute pains or gripings in us. That these ideas of sickness and pain are not in the manna, but effects of its operations on us, and are nowhere when we feel them not: this also everyone readily agrees to. And yet men are hardly to be brought to think, that sweetness and whiteness are not really in manna ... Locke
	[...] the whole spatial world becomes a vast machine, including even the movements of animal bodies and those processes in human physiology which are independent of conscious attention. This world has no dependence on thought whatever, its whole machinery would continue to exist and operate if there were no human beings in existence at all. On the other hand, there is the inner realm whose essence is thinking, whose modes are such subsidiary processes as perception, willing, feeling, imagining, etc., In which realm, then, shall we place the secondary qualities? The answer given is inevitable. We can conceive the primary qualities to exist in bodies as they really are; not so the secondary.	"In truth they can be representative of nothing that exists out of the mind." They are, to be sure, caused by the various effects on our organs of the motions of the small insensible parts of the bodies. Burtt
Hume	Hume Be a philosopher; but, amidst all your philosophy, be still a man.	Thus there is a direct and total opposition betwixt our reason and senses [...] When we reason from cause and effect, we conclude, that neither color, sound, taste, nor smell have a continued and independent existence. When we exclude these sensible qualities there remains nothing in the universe, which has such an existence. Hume
Leibniz	If we imagine a machine so constructed as to produce thought, sensation, perception, we may conceive it magnified — to such an extent that one might enter it like a mill. This being supposed, we should find in it on inspection only pieces which impel each other, but nothing which can explain a perception. It is in the simple substance, therefore, — not in the compound, or in the machinery, — that we must look for that phenomenon [...] § There is nothing besides perceptions and their changes to be found in the simple substance. Leibniz	Leibniz
	History 2: Young, Helmholtz, Maxwell, Weyl, Schrodinger, Feynman