Comparison is never out of thought. As soon as we see a cigarette, whether we are aware of it or not, we compare it to another cigarette; also to what isn’t a cigarette. If we had not done something like this before, we should not have known it was a cigarette and should not have been able to call it that.

There is no situation as to things, where comparison is not possible. A cigarette may be compared to a cigarette of yesterday, another brand of cigarette, and to anything not a cigarette. A cigarette may be compared to a table when the wholeness of a cigarette is thought of and the wholeness of a table with a white tablecloth is thought of. Or a cigarette may be compared to a table by saying both cost money. Or a cigarette may be compared to a table by saying both are in a room. Or a cigarette may be compared to a table by saying both can be touched.

Comparisons are of all kinds; for likenesses are of all kinds. Some are obvious, some hidden, some surprising, some humorous—all are comparisons.

When many things are in a mind, in some way they have all been compared. The fact alone that they are in one mind means that a likeness has been given them, as they couldn’t be in one mind unless they had the possibility-of-being-in-that-mind in common.

Comparisons are of things as resting and things as moving. Life can be compared to a river; so can a heavy flow of blood; so can water in a glass. The first two comparisons concern a river as acting; the third, the river as being, as a noun.

Comparison unifies and separates. When things are compared, they are brought together; but when what is common between them is asserted, what is not common is felt more definitely and strongly.

Are there any two things that cannot be compared? The answer is, No: the mere placing of two things in thought at the same time gives them a likeness: they are being thought of at the same time, therefore they have same-timeness in common. To ask how can a clock and a blood cell be compared, is already to compare them: we have been thinking of them in the same minute. Of course, one could then go finding similarities; and there are an indefinite number of such: really an indefinite number. A clock and a blood cell are energetic; they are both important to man; they both can be found in Cincinnati (and all other places); they both can be described in words; they both can have things happen to them; they both can be possessed by a girl; they both are objects of science; they both have parts; they both can be considered small as to the sun; and so on and so on.

The reason that things can be indefinitely compared, is that all things have an indefinite number of forms; and these forms can, as to the separate things, be each compared.

Let us take a girl and a tiger.

A form of a girl is height. The height of a girl and the height of a tiger can be compared.

There is color. The color can be compared.

There is motion. The motion can be compared.

There is sensation. Sensations can be compared.

There is attitude to humans. This attitude can be compared.

There is preference as to dwellings.  The preferences can be compared.

And so with all forms.

Comparison is important in logic and poetry; poetry and logic are akin here. To say that an ox cart has something in common with an airplane, as they both can get to San Francisco, is strictly logical. To compare the slow, somewhat painful meditations of a passenger in an airplane, to the motion of an ox cart, may make for good prose or verse; but there is logic, too. If there are obstruction and slowness to the motion of an ox cart, and there are obstruction and slowness to certain thoughts, then these thoughts can be compared to the ox cart.

The notion can, literarily, be presented this way:

Mr. Aylesworth, passenger on the plane from Chicago to San Francisco, had his body carried by the softly, immensely speeding machine in air, hundreds of miles, as the minutes proceeded; but his thoughts about his daughter Ellen, in his pained doze, moved with the uncertainty, impediment, slowness of an ox cart, a hundred years ago, lumbering over the mountainous land he was unimpededly crossing in the night.

The logical proposition in the above paragraph is this: If Mr. Aylesworth’s thoughts, considered as motion, about his daughter Ellen were obstructed and slow, then they were the same as the motion of the ox cart in the 1840s, considered as obstructed and slow.

Logic is just as much in a conditional statement as in an indicative one: that is, it is just as true to say, If John is like Harry and Harry is like Barbara, then John is like Barbara—as it is to say, John is like Harry; Harry is like Barbara; John is like Barbara. Logic is a matter of forms clearly put.

The comparisons of logic and poetry are essentially akin. Strangeness of imagination may be in poetic comparison, yet there is logic.

Suppose one said:

The purpose of the line is—partly at least—to ally in a person’s mind the reality of a black train and cream. It is important that objects be imaginatively and sincerely unified; and this means that they be compared.

Logically, the line may be justified this way: A contemporary train in the night, on smooth tracks, may be considered as moving softly, curvedly, flowingly on tracks. Cream can be considered as moving softly, curvedly, flowingly. There is also a heaviness in space to a train, and a heaviness to cream. The proposition may be expressed conditionally: If a train in the night can be seen as moving heavily in space, and softly, curvedly, and flowingly, then it is like cream, when this is considered as moving heavily in space, and softly, curvedly, and flowingly.

If the line is sincere, then the train and cream were seen as having the things implied in common. When, in imagination, two things ordinarily not seen as alike, are seen as alike, and seen with sincerity by the whole self, there always is logic.

The line I have quoted could be made bolder. I could say:

Here the comparisons are more intricate, more indirect. Even so, there is a logic. In metaphor, as in simile, in every poetic figure (and there is comparison in some way in all poetic figures) there is logic. Further, as much as the poetry having the metaphor or other poetic figure, is good, the logic is important, strong, praiseworthy—and like the logic of arithmetic, or physics at its best, or the syllogism at its most effective.

The two aspects of feeling: the pleasure-pain aspect and the knowing-not knowing aspect, both constantly compare. The principle in the comparison made by a person who is “emotional” and a person who is clear, is the same.

It should be seen that comparison is relation affirmed; and that therefore, this definition is supplementary to and supplemented by the definition of Relation.