• elementary physical response (secondary signal) of the photoreceptor;

The main thing is that it really exists. And Democritus was the first to discover it. Sextus Empiricus writes: “As I said earlier, physicists have circulated from time immemorial a certain ancient opinion that like is knowable for like. As you know, Democritus also gives proofs for him, and Plato, as you know, touches him in passing in Timaeus. But Democritus bases his proof both on animate and inanimate, because “animals, ” he says, “gather in herds with homogeneous animals (for example, doves with doves and cranes with cranes, and so on, all the rest are unreasonable). In the same way [it happens] in the inanimate, as, for example, one can see on seeds when they are sown through a sieve, and on pebbles in a whirlpool. Here, on the one hand, when shaking the sieve, lentils with lentils, barley with barley, and wheat with wheat are located separately; on the other hand, in accordance with the movement of the wave, oblong pebbles tend to one place with oblong ones, and rounded pebbles - with rounded ones, as if the similarity contained in them contains something that unites these things ”. (Sextus Empiricus. Works. T. 1. M., " Thought", 1976. р. 83)

Indeed, the sensory organs are arranged by nature in such a way that each receptor (each cell of the receptive sieve) has its own narrowly defined specialization, so it “recognizes” only what it “knows”. And he only knows that he knows his rule.

The rule is the main element of active knowledge. Such is known by knowledge of such objects. So the rule of any receptor is a kind of aperture of the receptive sieve through which only the data known to this rule pass. The receptor rule is narrowly specialized and passes into the phase of mental excitement (sensation) only when receiving primary data of a strictly defined (by this rule) type. And in this regard, it is a very subtle analysis tool.

Democritus was the first to come up with the idea of ​ ​ a receptive sieve. The idea is absolutely correct. And we took full advantage of it. In terms of its influence on this study of the material nature of the mental sensations of an object, so its idea is worth much more than an entire section of modern psychology devoted to sensations. Moreover, psychology has studied this issue quite superficially. But this is why no one has yet formulated the idea of ​ ​ receptive diversity better than Democritus? Are psychologists not familiar with his philosophy?

Marxist philosophy about sensations has the following opinion: “Sensation is the result of processing by the central nervous system

(the brain) of nerve impulses that were formed as a result of the effect of an external stimulus on the nerve endings of the sensory organs (for example, on the auditory, optic or olfactory nerve)" (Dialectical and historical materialism. M., Politizdat, 1971. р. 139). This is an erroneous opinion, since only receptors feel, and they are not in the brain. Marxist philosophy disgraces this science for the umpteenth time, while hundreds of doctors of philosophical sciences have been polishing this demagogy for decades...

Hegel is much better: “Sensation is a form of vague activity of the spirit in its unconscious and alien to reason individuality, in which all certainty is still immediate; in its content, as well as in the opposition of the objective and the subject, it is given in an as yet undeveloped form, belongs to the highly isolated, natural uniqueness of the subject. The content of sensation is precisely because it is limited and transient, because it refers to natural, immediate being, to that, therefore, that is qualitative and finite" (Hegel. Encyclopedia of Philosophical Sciences. T. 3. M., " Thought", 1977. р. 104). Sensation is a form of mental activity. And this is really so, only this is not enough.