  Telesio rejected the traditional concept of sense organs, replacing it with a mechanistic explanation of sense perception (DRN books V–VII). In his opinion, to speak of sense organs is inappropriate, as the so-called sense organs are nothing else than “parts of the body which are either more subtle or soft than others, or perforated and open. One should not believe in the slightest that they are made thus in order to offer some capacity or support of perceiving to the sensitive soul (which seems to be the duty of organs), but in order to provide an easy and open entry to the forces of external things and to those things themselves.” (DRN book I, ch.VI; vol. I, p. 68). What is perceived are not the forms or species of things as the Aristotelians believed, but impulses of light and air (DRN book V, ch. VIII; vol. II, 254; for the rejection of species see DRN book VII, ch. XXX–XXXIII against the Aristotelian and ch. XVIII–XXIX against the Galenic theory; Telesio's rejection of species was taken up by Hobbes, Leviathan book I, ch. I “De sensu”). As the sense of touch provides the most narrow contact between outer object and sensing spirit, it assumes the role of the primary sense, which was traditionally identified with the sense of vision (DRN book VII, ch. IX, vol. III, p. 34.) The informatio theory being rejected, Telesio comes close to a neuronal explanation of sense perception, which is a mechanical process arising from the transfer of tactile impressions through the nerves to the brain. It is the spirit residing in the brain which experiences nervous dilatations and contractions, and which judges these sensations according to the basic scheme of pleasure and pain, giving out corresponding reactions like moving towards something or avoiding contact (DRN book VII ch. II–V). Strictly speaking, sense perception is a sensation of sensing (sensus sensus) which takes place in the brain: “Sense perception can only be the perception of the activities of things and impulses in the air, and can only consist of the perception of [the spirit's] own passions, transformations and movements, particularly the latter. Indeed, the spirit perceives them because he perceives that it is affected by them, that it is being changed and moved.” (Vol. III, p. 6)