But when by reflection I perceive what the proposition implies, I remark that other things may ruminate besides oxen, and that the unknown multitude of things which ruminate form a mass, with which the unknown multitude of things having the attributes of oxen is either identical or is wholly comprised in it.  Which of these two is the truth I may not know, and if I did, took no notice of it when I assented to the proposition, all oxen ruminate; but I perceive, on consideration, that one or other of them must be true.  Though I had not this in my mind when I affirmed that all oxen ruminate, I can have it now; I can make the concrete objects denoted by each of the two names an object of thought, as a collective though indefinite aggregate; in other words, I can make the Extension of the names (or notions) an object of direct consciousness.  When I do this, I perceive that this operation introduces no new fact, but is only a different mode of contemplating the very fact which I had previously expressed by the words, all oxen ruminate.  The fact is the same, but the mode of contemplating it is different.  There is thus in all Propositions a judgment concerning attributes (called by Sir W. Hamilton a Judgment in Comprehension) which we make as a matter of course; and a possible judgment in or concerning Extension, which we may make, and which will be true if the former is true.’

From the lucid explanation here cited (and from a following paragraph too long to describe p. 433), we see that there is no real distinction between Judgments in Comprehension and Judgments in Extension; that the appearance of distinction between them arises from the customary mode of enunciation, which custom is here accounted for; that the addition to the theory of the Syllogism, for which Sir W. Hamilton takes credit, is alike troublesome and unprofitable.

The like may also be said about his other innovation, the Quantification of the Predicate.  Still more extensive are the changes (as stated by himself) which this innovation would introduce in the canons of Syllogism.  Indeed, when we read his language (Appendix to ’Lectures on Logic,’ pp. 291—­297) censuring generally the prior logicians from Aristotle downwards, and contending that ’more than half the value of logic had been lost’ by their manner of handling it—­we may appreciate the magnitude of the reform which he believed himself to be introducing.  The larger the reform, the more it behoved him to be sure of the ground on which he was proceeding.  But on this point we remark a serious deficiency.  After laying down, with appropriate emphasis, the valuable logical postulate, to state explicitly what is thought implicitly, on which, Sir W. Hamilton says,