Subsection 7. The internal senses.

There are three internal senses, so called because they are within the skull: common sense, imagination and memory. Their objects are not merely things present; they also perceive the sensory forms of future, past and absent things, forms previously received through the senses. This common sense is the judge or governor of the others, by which we distinguish all differences between objects. It is not through my eye that I know I see, nor through my ear that I know I hear, but through my common sense, which judges sounds and colours. The others are merely the organs that bring sensory forms to be assessed; all their objects and all their functions therefore belong to it. Its organ or seat is the front of the brain.

Fancy, or imagination, which some call the estimative or cogitative faculty, is strengthened, Fernel says, by frequent reflection. It is an internal sense that examines more fully the forms of present or absent things perceived by common sense, and retains them longer, recalling them to mind or inventing new ones of its own. During sleep this faculty is free, and often conceives strange, astonishing and absurd shapes, as we commonly observe in sick people. Its organ is the brain’s middle chamber; its objects are all the forms communicated to it by common sense, which it compares to invent countless others for itself.

In people with melancholy this faculty is especially powerful and strong, and often does harm, producing many monstrous and extraordinary things, particularly when stirred by some terrifying object presented by common sense or memory. Imagination works forcefully in poets and painters, as their various inventions, grotesques and images show: Ovid’s house of Sleep, Psyche’s palace in Apuleius, and so on. In humans it is subject to reason’s government, or at least should be; in other animals it has no superior and is their reason—all the reason they possess.

Memory stores all the forms brought in by the senses and records them like a good clerk, so that they are available when imagination and reason call for them. Its object is the same as imagination’s; its seat and organ is the back of the brain.

The states of these senses are sleep and waking, common to all creatures capable of sensation. Sleep, as Scaliger defines it, is a rest or suspension of the external senses and common sense, for the preservation of body and soul. When common sense rests, the external senses rest too. Imagination alone is free, together with its commander, reason, as is evident from dreams. These are of various kinds—natural, divine, demonic, and so on—and vary with the humours, diet, actions, objects of perception and other circumstances. Artemidorus, Cardano and Sambucus, with their respective interpreters, have written large volumes about them.

This suspension of the senses comes from a checking of the spirits, whose passage is blocked. The blockage is caused by vapours rising from the stomach and filling the nerves through which the spirits should travel. When these vapours have dispersed, the passage opens and the spirits perform their usual duties. Waking, then, is the activity and movement of the senses caused by the spirits distributed throughout the body.