the senses as simply satellites and messengers (see Cicero, De Legibus, quoted Lipsius' Manud. ad Philos. Stoic. ii. 11), and place above them a power of comprehension, kaτdλŋyıs, which judges the information given by the senses. The Epicureans thought the senses never deceive, but then they give us things only as they appear. The Academics maintained that the intellect and not sense is the judge of truth: "Non esse judicium veritatis in sensibus, mentem volebant rerum esse judicem." They held "sensus omnes hebetes et tardos esse arbitrabantur, nec percipere ullo modo eas res, quæ subjectæ sensibus viderentur; quæ essent aut ita parvæ, ut sub sensum cadere non possent; aut ita mobiles et concitatæ, ut nihil unquam unum esse constans" (Acad. Quæs. i. 8), and so reality becomes a matter of opinion or probability.

Augustine follows out the views of the Greek philosophers, specially those of Aristotle. Thus in his exposition of Categoria Decem ex Aristotele Decerptæ, v.: "Sunt igitur illa quæ aut percipimus sensibus, aut mente et cogitatione colligimus. Sensibus tenemus quæ aut videndo, aut contrectando, aut audiendo, aut gustando, aut odorando cognoscimus. Mente, ut cum quis equum, aut hominem, aut quodlibet animæ viderit, quanquam unum corpus esse respondeat, intelligi tamen multis partibus esse concretum." He illustrates his meaning elsewhere: "Si quis remum frangi in aqua opinatur, et cum inde aufertur integrari; non malum habet internuntium, sed malus est judex. Nam ille pro sua natura non potuit aliter sentire, nec aliter debuit; si enim aliud est aer, aliud aqua, justum est ut aliter in aere, aliter in aqua sentiatur" (Lib. de Ver. Relig. c. 33). The subject is discussed Contra Academicos, 24-28. Anselm treats the subject in much the same way as Augustine (Dialog. de Verit. vi.). He says the error is to be ascribed, not to the senses, but to the judgment of the mind: "Falsitas non in sensibus sed opinione." It is the mind that imparts the false appearances, as the boy fears the sculptured dragon. "Unde contingit ut sensus interior culpam suam imputet sensui exteriori.'

In modern times, metaphysicians have vacillated between the Platonic and Aristotelian theories; some, as Kant and Hamilton, making every perception partly subjective, and others ascribing the supposed deception to wrong deductions from the matter supplied by the senses. The Sensational School of France and T. Brown make all external perception an inference from sensations in the mind, and refer the mistakes to wrong reasoning.

CHAPTER IV.

APPARENT DECEPTION OF THE SENSES.

ALMOST all forms of idealism (the system which supposes certain of our supposed cognitions to be creations of the mind), and all forms of scepticism (the system which would set aside all our cognitions), plead the deceitfulness of the senses. Our senses are not to be trusted in some things, says the idealist, and we are to determine by reason when they are to be trusted. Our senses delude us in some things, says the sceptic, and we may therefore distrust them in all. It is of vast moment to stop these errors at the point at which they flow out, by showing that the senses, meaning our original perceptions through the senses, can all be trusted in regard to the special testimony which they furnish.

But how, it is asked, does the stick in the water, felt to be straight by the sense of touch, seem crooked to the sense of sight? The answer is, that the knowledge of the shape of an object does not primarily fall under the sense of sight, and that when we determine whether a stick is or is not straight, by the sense of sight, it is by a process of inference in which we have laid down the rule that objects that give a certain figure before the eye are crooked, a rule correct enough for common cases, but not applicable to those in which the rays of light are refracted in passing from one medium to another. Why does a boy seem a man, and a man a giant, in a mist, whereas, if you clear away the mist, both are instantly reduced to their proper dimensions? A reply

can easily be given. We have laid down the rule that an object seen so dimly must be distant; but an object appearing of such dimensions at a distance must be large: and the phenomenon is felt to be a deception only by those who are not accustomed to move in the mist. Why does a mountain, viewed across an arm of the sea, seem near, while the same mountain, seen at an equal distance beyond an undulated country studded with houses and trees, appears very remote ? The answer is, not that the eye has deceived us, but that we have made a mistaken application of a rule usually correct, that an object must be near when few objects intervene between us and it; and it is to be noticed that those who are accustomed to look across sheets of water commit no such mistakes, for they have acquired other means of measuring distance. Again, we have found it true, in cases so many that we cannot number them, that when we are at rest and the image of an object, say a carriage, passes across the vision, the object must be in motion. That rule is accurate in all cases similar to those from which it was derived; but it fails the landsman when, feeling as if he were at rest in the ship, he infers that the shore is moving away from the vessel. In all such cases we see that it is not the senses, that is, the natural and original perceptions of the senses having the authority of God, which deceive us, but rules formed or applied illegitimately by ourselves.

CHAPTER V.

THE ESSENTIAL QUALITIES OF MATTER.

LOCKE speaks of the Primary Qualities as being in matter in whatever state it may be. Reid speaks of them as being directly perceived by us. These two marks coincide, presenting the same truth under two different aspects, the one objective the other subjective. They are the essential qualities of matter known in all its states, and known at once and intuitively. They are two in number.

I. There are the Qualities of Matter by which it occupies Space and is contained in Space, that is, Extension. We have this knowledge, I believe, through each of our senses; for in each we know the corresponding organs as extended and out of each other, and through two of the senses we know objects beyond our bodily frame as extended. Hamilton represents extension as a necessary constituent of our notion of Matter, and evolves it from "two catholic conditions of matter: (1) the occupying space, and (2) the being contained in space. Of these, the former affords (A) Trinal Extension, explicated again into (1.) Divisibility, (II.) Size, containing under it Density or Rarity, (III.) Figure; and (B) Ultimate Incompressibility; while the latter gives (A) Mobility, and (B) Situation. Neglecting subordination, we have thus eight proximate attributes: 1. Extension; 2. Divisibility; 3. Size; 4. Density or Rarity; 5. Figure; 6. Incompressibility absolute; 7. Mobility; 8. Situation."1

1 Hamilton's Reid, Note D, p. 848.

II. The Qualities which one body exercises in reference to another; in other words, the Properties or Forces of matter. I have expended much labor in vain if I have not shown, in previous sections, that here we have a necessary conviction. In the visual and locomotive senses, we know an extra-organic object as affecting us and our organism. All this seems to be involved in our perception, and to be a native conviction of the mind, to which it is ever prompted, and from which it can never be delivered. Not only so, we are ever led to look for a producing cause, even of our purely organic affections in the ear and palate and nostrils. A knowledge of power, and a conviction of power being in exercise, are thus involved in our very perceptions through the senses.

Adhering to these views, we must set aside at once. two opposite doctrines which have had the support each of a number of eminent metaphysicians or metaphysical speculators. The one is that matter is known as possessing no other quality than extension. This error originated with Descartes, and has prevailed extensively among those metaphysicians who have felt his influence. But the view is opposed to that intuition which represents all matter as having and exercising energy. On the other side, there are speculators who maintain that all the phenomena of matter can be explained by supposing it to possess potency. This mistake sprang from Leibnitz, who supposed that the universe of matter (and of mind) was composed of monads having power, and to which the mind imparted the relation of space. But the dynamical theory of body, so far as it denies the existence of space, and body as occupying space, is utterly inconsistent with that fundamental conviction, of which the mind can never be shorn, which declares that the matter which has force must be extended, and