Sextus says that a man born with less than the usual number of senses, would form altogether different ideas of the external world than those who have the usual number, and as our ideas of objects depend on our mental images, a greater number of sense organs would give us still different ideas of outward reality.[1] The strong argument of the Stoics against such reasoning as this, was their doctrine of pre-established harmony between nature and the soul, so that when a representation is produced in us of a real object, a [Greek: kataleptike phantasia],[2] by this representation the soul grasps a real existence. There is a [Greek: logos] in us which is of the same kind, [Greek: syngenos], or in relation to all nature. This argument of pre-established harmony between the faculties of the soul and the objects of nature, is the one that has been used in all ages to combat philosophical teaching that denies that we apprehend the external world as it is. It was used against Kant by his opponents, who thought in this way to refute his teachings.[3] The Sceptics could not, of course, accept a theory of nature that included the soul and the external world in one harmonious whole, but Sextus in his discussion of the third Trope does not refute this argument as fully as he does later in his work against logic.[4] He simply states here that philosophers themselves cannot agree as to what nature is, and furthermore, that a philosopher himself is a part of the discord, and to be judged, rather than being capable of judging, and that no conclusion can be reached by those who are themselves an element of the uncertainty.[5] [1] _Hyp._ I. 96-97. [2] _Adv. Math._ VII. 93. [3] Ueberweg _Op. cit._ 195. [4] _Adv. Math._ VII. 354. [5] _Hyp._ I. 98-99. _The Fourth Trope_. This Trope limits the argument to each separate sense, and the effect is considered of the condition of body and mind upon sense-perception in relation to the several sense-organs.[1] The physical states which modify sense-perception are health and illness, sleeping and waking, youth and age, hunger and satiety, drunkenness and sobriety. All of these conditions of the body entirely change the character of the mental images, producing different judgments of the color, taste, and temperature of objects, and of the character of sounds. A man who is asleep is in a different world from one awake, the existence of both worlds being relative to the condition of waking and sleeping.[2]