2. The trains of thought which pass in our minds, are sequences, the items of which are connected in three principal ways: 1st, as cause and effect; 2dly, as resembling; 3dly, as included under the same name. A short illustration of each of these cases will {187} complete the account of predication, as a contrivance for marking the order of ideas. To illustrate a sequence, connected as Cause and Effect, let me suppose that I have a flint and steel in my hand, which I am about to strike, one against the other, but at that instant perceive a barrel of gunpowder open, close before me. I withhold the stroke in consequence of the train of thought which suggests to me the ultimate effect. If I have occasion to mark the train, I can only do it by a series of Predications, each of which marks a sequence in the train of causes and effects. "I strike the flint on the steel," first sequence. "The stroke produces a spark," second sequence. "The spark falls on gunpowder," third sequence. "The spark ignites the gunpowder," fourth sequence. "The gunpowder ignited makes an explosion," fifth sequence. The ideas contained in these propositions must all have passed through my mind, and this is the only mode in which language enables me to mark them in their order.[55] [Editor's footnote 55: It is necessary again to notice the consistent omission, throughout the author's theory of Predication, of the element Belief. In the case supposed, the ideas contained in all the propositions might have passed through the mind, without our being led to assert the propositions. I might have thought of every step in the series of phenomena mentioned, might have pictured all of them in my imagination, and have come to the conclusion that they would not happen. I therefore should not have made, either in words or in thought, the predication, This gunpowder will explode if I strike the flint against the steel. Yet the same ideas would have passed through my mind in the same order, in which they stand in the text. The only deficient link would have been the final one, the Belief.--_Ed._] {188} The sequences of which the items are connected by Resemblance will not require much illustration. I see A, who suggests B to me by his stature. B suggests C by the length of his nose. C suggests D by the similarity of their profession, and so on. The series of my thoughts is sufficiently obvious. How do I proceed when I have occasion to mark it? I use a series of predications. "I see A;" this predication marks the first item, my sight of A. "A is tall," the second. "A man of like tallness is B," the third; and so on.