Aristotle On Youth and Old Age,On Life and Death,On Breathing-Part 3

The same phenomenon is evident both in plants and in animals, and inplants we note it both in their propagation by seed and in graftsand cuttings. Genesis from seeds always starts from the middle. Allseeds are bivalvular, and the place of junction is situated at thepoint of attachment (to the plant), an intermediate part belongingto both halves. It is from this part that both root and stem ofgrowing things emerge; the starting-point is in a central positionbetween them. In the case of grafts and cuttings this isparticularly true of the buds; for the bud is in a way thestarting-point of the branch, but at the same time it is in acentral position. Hence it is either this that is cut off, or intothis that the new shoot is inserted, when we wish either a newbranch or a new root to spring from it; which proves that the point oforigin in growth is intermediate between stem and root.Likewise in sanguineous animals the heart is the first organdeveloped; this is evident from what has been observed in thosecases where observation of their growth is possible. Hence inbloodless animals also what corresponds to the heart must developfirst. We have already asserted in our treatise on The Parts ofAnimals that it is from the heart that the veins issue, and that insanguineous animals the blood is the final nutriment from which themembers are formed. Hence it is clear that there is one function innutrition which the mouth has the faculty of performing, and adifferent one appertaining to the stomach. But it is the heart thathas supreme control, exercising an additional and completing function.Hence in sanguineous animals the source both of the sensitive and ofthe nutritive soul must be in the heart, for the functions relative tonutrition exercised by the other parts are ancillary to the activityof the heart. It is the part of the dominating organ to achieve thefinal result, as of the physician's efforts to be directed towardshealth, and not to be occupied with subordinate offices.Certainly, however, all saguineous animals have the supreme organ ofthe sensefaculties in the heart, for it is here that we must lookfor the common sensorium belonging to all the sense-organs. These intwo cases, taste and touch, can be clearly seen to extend to theheart, and hence the others also must lead to it, for in it theother organs may possibly initiate changes, whereas with the upperregion of the body taste and touch have no connexion. Apart from theseconsiderations, if the life is always located in this part,evidently the principle of sensation must be situated there too, forit is qua animal that an animal is said to be a living thing, and itis called animal because endowed with sensation. Elsewhere in otherworks we have stated the reasons why some of the sense-organs are,as is evident, connected with the heart, while others are situatedin the head. (It is this fact that causes some people to think that itis in virtue of the brain that the function of perception belongs toanimals.).