[G] See Ibn Sînâ’s «_Qânûn_,» Section 2, where he says: As to the nutritive power, it is that power which transforms the nutriment into a resemblance with the nourishment-taker, in order that this nutriment may succeed in the stead of what shall be wasted, and attach itself to the taker instead of the waste.--See also «_Kitâb-ul-Najât_,» by Ibn Sînâ. SECTION FIFTH =Specification of the Animal Powers, and Mention of the Need there is for Each One of Them.= I affirm that every animal is sentient, and hence it moves itself at will, in some sort of motion; and that every animal moves itself in some sort of motion at will, and hence it is sentient; since sensation in what does not move itself at will is wasted and useless, and the lack of it in what does move itself at will is harmful; whereas Nature, owing to that much of Divine Providence as has been joined to her, gives nothing whatever that is either wasted or harmful, nor witholds either the necessary or the useful. Perhaps some one may speak out here and object to us that shellfish are of such as feel (are sentient) and yet do not move themselves at will. This objection, however, will speedily vanish on experiment; for shellfish, although they do not move themselves from their places in a sort of organic (mechanical) locomotion at will, yet they do more or less shrink themselves up and spread out inside of their shells, as I have witnessed with mine own eyes on having tried the experiment more than once, in that I turned the shell over onto its back, so that its position for drawing nourishment became separated from the ground; whereupon it ceased not to struggle until it had again stood in a position that made it easy for it to draw in nourishment from the muddy bottom. And now that this has become surely certain for us, we shall further say: That whereas Divine Wisdom has decreed that an animal moving itself at will shall be composed of the four elements, and as such animal would not be secure against the evils of mishaps in its successive change of places during locomotion, it has been fitted out with the touching power (sense of touch), so as to flee through it from unfit places, and seek those that are fit. And whereas any such animal’s constitution (make-up) cannot get on without the getting of nourishment; and as its gaining its food is a sort of free will effort; and as some articles of food suit it, and others do not,--it has been fitted out with the tasting power (sense of taste). These two powers (senses) are both useful and necessary in life: the rest are useful, not necessary.