The same light or tone alters decidedly in different surroundings.  Perspective in paintings depends on the angle at which the picture is suspended.[2] With Diogenes this Trope is the seventh,[3] and his exposition of it is similar, but as usual, shorter.  Both Sextus and Diogenes give the illustration[4] of the neck of the dove differing in color in different degrees of inclination, an illustration used by Protagoras also to prove the relativity of perception by the senses.  “The black neck of the dove in the shade appears black, but in the light sunny and purple."[5] Since, then, all phenomena are regarded in a certain place, and from a certain distance, and according to a certain position, each of which relations makes a great difference with the mental images, we shall be obliged also by this Trope to come to the reserving of the opinion.[6]

    [1] Hyp. I. 118.

    [2] Hyp. I. 120.

    [3] Diog.  IX. 11, 85.

    [4] Hyp. I. 120; Diog.  IX. 11, 86.

    [5] Schol. zu Arist. 60, 18, ed.  Brandis; Pappen. Er. 
        Pyrr.  Grundzuege, p. 54.

    [6] Hyp. I. 121.

The Sixth Trope.  This Trope leads to [Greek:  epoche] regarding the nature of objects, because no object can ever be presented to the organs of sense directly, but must always be perceived through some medium, or in some mixture.[1] This mixture may be an outward one, connected with the temperature, or the rarity of the air, or the water[2] surrounding an object, or it may be a mixture resulting from the different humors of the sense-organs.[3] A man with the jaundice, for example, sees colors differently from one who is in health.  The illustration of the jaundice is a favorite one with the Sceptics.  Diogenes uses it several times in his presentation of Scepticism, and it occurs in Sextus’ writings in all, as an illustration, in eight different places.[4] The condition of the organ of the [Greek:  hegemonikon], or the ruling faculty, may also cause mixtures.  Pappenheim thinks that we have here Kant’s idea of a priori, only on a materialistic foundation.[5] A careful consideration of the passage, however, shows us that Sextus’ thought is more in harmony with the discoveries of modern psychiatry than with the philosophy of Kant.  If the sentence, [Greek:  isos de kai aute (he dianoia) epimixian tina idian poieitai pros ta hypo ton aistheseon anangellomena],[6] stood alone, without further explanation, it might well refer to a priori laws of thought, but the explanation which follows beginning with “because” makes that impossible.[7] “Because in each of the places where the Dogmatics think that the ruling faculty is, we see present certain humors, which are the cause of mixtures.”  Sextus does not advance any opinion as to the place of the ruling faculty in the body, which is, according to the Stoics, the principal part of the soul, where ideas, desires,