[Footnote 185: Diog. Ap. Fr. vi. [Greek: kai\ e)sti mêde\ e(\n o(/, ti mê\ mete/chei tou/tou] (air). [Greek: Mete/chei de\ ou)de\ e(\n o(moi/ôs to\ e(/teron tô=| e(te/rô|; a)lla\ polloi\ tro/poi\ kai\ au)tou\ tou= a)e/ros kai\ tê=s noê/sio/s ei)sin.] Aristotel. De Animâ, i. 2, p. 405, a. 21. [Greek: Dioge/nês d', ô(/sper kai\ e(teroi/ tines, a)e/ra [u(pe/labe tê\n psuchê/n]], &c.] [Footnote 186: Diog. Ap. Fr. vi. [Greek: kai\ pa/ntôn zô/ôn dê\ ê( psuchê\ to\ au)to/ e)stin, a)ê\r thermo/teros me\n tou= e)/xô e)n ô(=| e)sme/n, tou= me/ntoi para\ tô=| ê(eli/ô| pollo\n psuchro/teros.]] [Footnote 187: Diogen. Apoll. Fr. v. ch. 38, Panz.] [Side-note: Physiology of Diogenes--his description of the veins in the human body.] The intelligence of men and animals, very unequal in character and degree, was imbibed by respiration, the inspired air passing by means of the veins and along the blood into all parts of the body. Of the veins Diogenes gave a description remarkable for its minuteness of detail, in an age when philosophers dwelt almost exclusively in loose general analogies.[188] He conceived the principal seat of intelligence in man to be in the thoracic cavity, or in the ventricle of the heart, where a quantity of air was accumulated ready for distribution.[189] The warm and dry air concentrated round the brain, and reached by veins from the organs of sense, was the centre of sensation. Taste was explained by the soft and porous nature of the tongue, and by the number of veins communicating with it. The juices of sapid bodies were sucked up by it as by a sponge: the odorous stream of air penetrated from without through the nostrils: both were thus brought into conjunction with the sympathising cerebral air. To this air also the image impressed upon the eye was transmitted, thereby causing vision:[190] while pulsations and vibrations of the air without, entering through the ears and impinging upon the same centre, generated the sensation of sound. If the veins connecting the eye with the brain were inflamed, no visual sensation could take place;[191] moreover if our minds or attention were absorbed in other things, we were often altogether insensible to sensations either of sight or of sound: which proved that the central air within us was the real seat of sensation.[192] Thought and intelligence, as well as sensation, was an attribute of the same central air within us, depending especially upon its purity, dryness, and heat, and impeded or deadened by moisture or cold. Both children and animals had less intelligence than men: because they had more moisture in their bodies, so that the veins were choked up, and the air could not get along them freely to all parts. Plants had no intelligence; having no apertures or ducts whereby the air could pervade their internal structure. Our sensations were pleasurable when there was much air mingled with the blood, so as to lighten the flow of it, and to carry it easily to all