These three subsystems are part of the psychic system, from which the mind emerges. They do not necessarily act on the same materials at a given moment. Identical perceptions are not organized in the same way in these three levels of the mind.
To illustrate this analysis, Spinoza takes the example of the impact of a sunset on a person's thoughts. A first series of information about the sun comes from the way it is integrated in the physiological dynamics17 that are activated when the solar rays reach the retina.
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This activity unfolds automatically in a nonconscious way. The organism will then create in the mind representations derived from the activity of the sensory nervous system. The mechanisms that translate nervous impulses into thoughts are unknown. However, once these representations enter the mind, they first follow psychological laws such as those of Spinoza's imagination. Given that these first mechanisms are primitive, they will create a kind of illusion that inspires poets but not the astronomer: 18
When we look at the sun, we imagine it as about two hundred feet away from us, an error which does not consist simply in his imagining, but in the fact that while we imagine it in this way, we are ignorant of its true distance and of the cause of this imagining. For even if we later come to know that it is more than six hundred diameters of the earth away from us, we nevertheless imagine it as near. For we imagine the sun near not because we do not know its true distance, but because an affection of our body involves the essence of the sun insofar as our body is affected by the sun. (Spinoza, 1677a, Ethics, II, proposition XXXV, scholium, p. 53f)
Given that thoughts are not conscious of being fabricated by the nervous system, the individual has the impression that his perceptions correspond to reality. Siegfried Frey has recently indicated, with research to back it up, that this impression is not negotiable, even when various lectures and trainings indicate that these impressions are illusions. In this way, Frey and Masters explain the incredible impact of the visual media (especially television) on citizens. 19 Spinoza's imagination is thus a type of thinking that perceives the sun as a sphere that descends behind the horizon, and reacts as if what is perceived is what is. Imagination has no more critical sense than a camera.