am an
"old bird" as Mr. Smith himself calls me; a Simorg, an "all-knowing Bird of
Ages" in matters of cyclometry.

The curious phenomena of thought here exhibited illustrate, as above said,
a remark I have long ago made on the effect of proper study of logic. Most
persons reason well enough on matter to which they are accustomed, and in
terms with which they are familiar. But in unaccustomed matter, and with
use of strange terms, few except those who are practised in the
abstractions of pure logic can be tolerably sure to keep their feet. And
one of the reasons is easily stated: terms which are not quite familiar
partake of the vagueness of the X and Y on which the student of logic
learns to see the formal force of a proposition independently of its
material elements.

I make the following quotation from my fourth paper on logic in the
_Cambridge Transactions_:

"The uncultivated reason proceeds by a process almost entirely material.
Though the necessary law of thought {121} must determine the conclusion of
the ploughboy as much as that of Aristotle himself, the ploughboy's
conclusion will only be tolerably sure when the matter of it is such as
comes within his usual cognizance. He knows that geese being all birds does
not make all birds geese, but mainly because there are ducks, chickens,
partridges, etc. A beginner in geometry, when asked what follows from
'Every A is B,' answers 'Every B is A.' That is, the necessary laws of
thought, except in minds which have examined their tools, are not very sure
to work correct conclusions except upon familiar matter.... As the
cultivation of the individual increases, the laws of thought which are of
most usual application are applied to familiar matter with tolerable
safety. But difficulty and risk of error make a new appearance with a new
subject; and this, in most cases, until new subjects are familiar things,
unusual matter common, untried nomenclature habitual; that is, until it is
a habit to be occupied upon a novelty. It is observed that many persons
reason well in some things and badly in others; and this is attributed to
the consequence of employing the mind too much upon one or another subject.
But those who know the truth of the preceding remarks will not have far to
seek for what is often, perhaps most often, the true reason.... I maintain
that logic tends to make the power of reason over the unusual and
unfamiliar more nearly equal to the power over the usual and