The inquiry has now reached a stage at which we may stop to consider what result has been reached, especially in regard to the question whether the two words [Greek: harmonia] and [Greek: tonos] denote two sets of musical forms, or are merely two different names for the same thing. The latter alternative appears to be supported by several considerations. 1. From various passages, especially in Plato and Aristotle, it has been shown that the modes anciently called [Greek: harmoniai] differed in pitch, and that this difference in pitch was regarded as the chief source of the peculiar ethical character of the modes. 2. The list of [Greek: harmoniai] as gathered from the writers who treat of them, viz. Plato, Aristotle, and Heraclides Ponticus, is substantially the same as the list of [Greek: tonoi] described by Aristoxenus (p. 18): and moreover, there is an agreement in detail between the two lists which cannot be purely accidental. Thus Heraclides says that certain people had found out a new [Greek: harmonia], the Hypo-phrygian; and Aristoxenus speaks of the Hypo-phrygian [Greek: tonos] as a comparatively new one. Again, the account which Aristoxenus gives of the Hypo-dorian [Greek: tonos] as a key immediately below the Dorian agrees with what Heraclides says of the Hypo-dorian [Greek: harmonia], and also with the mention of Hypo-dorian and Hypo-phrygian (but not Hypo-lydian) in the Aristotelian _Problems_. Once more, the absence of Ionian from the list of [Greek: tonoi] in Aristoxenus is an exception which proves the rule: since the name of the Ionian [Greek: harmonia] is similarly absent from Aristotle. 3. The usage of the words [Greek: harmonia] and [Greek: tonos] is never such as to suggest that they refer to different things. In the earlier writers, down to and including Aristotle, [Greek: harmonia] is used, never [Greek: tonos]. In Aristoxenus and his school we find [Greek: tonos], and in later writers [Greek: tropos], but not [Greek: harmonia]. The few writers (such as Plutarch) who use both [Greek: tonos] and [Greek: harmonia] do not observe any consistent distinction between them. Those who (like Westphal) believe that there was a distinction, are obliged to admit that [Greek: harmonia] is occasionally used for [Greek: tonos] and conversely. 4. If a series of names such as Dorian, Phrygian, Lydian and the rest were applied to two sets of things so distinct from each other, and at the same time so important in the practice of music, as what we now call modes and keys, it is incredible that there should be no trace of the double usage. Yet our authors show no sense even of possible ambiguity. Indeed, they seem to prefer, in referring to modes or keys, to use the adverbial forms [Greek: dôristi], [Greek: phrygisti], &c., or the neuter [Greek: ta dôria], [Greek: ta phrygia], &c., where there is nothing to show whether 'mode' or 'key,' [Greek: harmonia] or [Greek: tonos], is intended. § 15. _The Systems of Greek Music._