d, we may sometimes learn, within the given limits,
all that there is to know: as all the bones of a particular animal, or
the list of English monarchs hitherto, or the names of all the members
of the House of Commons at the present time. Such cases, however, do not
invalidate the above logical truth that few general terms are
exhaustively known in their denotation; for the very fact of assigning
limits of time and place impairs the generality of a term. The bones of
a certain animal may be all examined, but not the bones of all animals,
nor even of one species. The English monarchs that have reigned hitherto
may be known, but there may be many still to reign.

The general terms, then, with which Logic is chiefly concerned, the
names of Causes and Kinds, such as gravitation, diseases, social events,
minerals, plants and animals, stand for some facts that are, or have
been, known, and for a great many other similar ones that have not been,
and never will be, known. The use of a general term depends not upon our
direct knowledge of everything comprised in its denotation, but upon our
readiness to apply it to anything that has its connotation, whether we
have seen the thing or not, and even though we never can perceive it; as
when a man talks freely of the ichthyosaurus, or of the central heat of
planets, or of atoms and ether.

Hence Universal Propositions, which consist of general terms, deceive
us, if we suppose that their predicates are directly known to be related
to all the facts denoted by their subjects. In exceptional cases, in
which the denotation of a subject is intentionally limited, such
exhaustive direct knowledge may be possible; as that "all the bones of a
certain animal consist of phosphate of lime," or that every member of
the present Parliament wears a silk hat. But what predication is
possible concerning the hats of all members of Parliament from the
beginning? Ordinarily, then, whilst the relation of predicate to subject
has been observed in some cases, in much the greater number of cases
our belief about it depends upon something besides observation, or may
be said (in a certain sense) to be taken on trust.

'All rabbits are herbivorous': why do we believe that? We may have seen
a few wild rabbits feeding: or have kept tame ones, and tried
experiments with their diet; or have read of their habits in a book of
Natural History; or have studied the anatomy and physiology of the
digestive system in many