With that spirit of observation for which they were so eminently remarkable, the ancients had long since remarked the constant connexion of certain peculiarities of outward form with particular modes of thinking—a correspondence between the physical and mental condition. It was in accordance with this view that Galen founded his celebrated doctrine of temperaments. His distinction of the sanguine, phlegmatic, choleric, and melancholic temperaments, was based upon the notion of the Greek philosophers, that there were four primary constituents of the human body corresponding to the four supposed elements of nature, and that the presence of the one or the other of these elements in excess occasioned the production of the different temperaments. According to the definition of the able physiologist Müller, the temperaments are peculiar, permanent conditions, or modes of mutual reaction of the mind and organism, and they are chiefly dependent on the relation which subsists between the strivings or emotions of the mind and the excitable structure of the body. Even if we may be disposed to contend that they are not absolutely _dependent_ on any particular constitution of the body, it must still be conceded that they are at least _associated_ with certain peculiarities of outward organisation, by which they may be readily recognised; so that the physical structure, the mental tendency, and the character of ideas, are always intimately connected. Thus persons of a sanguine or sensitive temperament are, for the most part, of moderate stature and _embonpoint_, with a smiling florid countenance, and light or chestnut hair. Their ideas, like their physiognomy, are all _couleur de rose_. Endowed with great excitability, they are easily moved; but impressions are not durable, giving place quickly to other and newer emotions. Hence their life is made up of transitions—now grave, now gay; now happy, now miserable: their feelings are perpetually changing, and impressions made upon their mobile minds become soon obliterated by some fresh object of attention. The phlegmatic, or elementary temperament, is characterised by a persistence during adult existence of the physical structure proper to early life. The body is loaded with cellular tissue and fat; the muscles are large, but soft, and with indistinct outlines; the countenance is pale; the physiognomy but little marked, and the features not sharply defined. Such persons are unexcitable, their sensations are dull, and the modes of reaction which they determine slow and apathetic; their ideas are clear, but they possess neither the quickness of conception and imagination of persons of the sanguine, nor the energy of action and strong passions of those of the choleric temperament. They love repose, and excel in occupations which demand patience and attention, of which they are possessed in a remarkable degree.