s-examination could not report what he saw; and he would
not think it fair to be condemned upon the testimony of his enemies.
Books have been written upon evidence, but three principles are all
that are needed in ordinary arguments. First, the person giving
testimony must be capable of observation; second, he must be able to
report accurately what he has observed; third, he must have a desire
to tell the exact truth.

Arguments from Example.

The third large division comprises arguments from example. That is, if
a truth be asserted of an individual, it can therefore be predicated
of the class to which the individual belongs. For instance, if the
first time a person saw a giraffe, he observed that it was eating
grass, he would be justified in saying that giraffes are herbivorous.
All gold is yellow, heavy, and not corroded by acid, though no one has
tested it all. However, every giraffe does not have one ear brown and
the other gray because the first one seen happened to be so marked;
neither is all gold in the shape of ten-dollar gold pieces. Only
common sense will serve to pick out essential qualities; but if
essential and invariable qualities be selected, the argument from the
example of an individual to all members of its class is very powerful.

Analogies resemble examples. In exposition they are used for
illustration; in argument they are employed as proofs. Though two
things belong to different classes of objects, they may have some
qualities that are similar, and so an argument may be made from one to
another. "Natural Law in the Spiritual World" is a book written to
show how the physical laws hold true in the region of spirit. It is
not because an enemy sowed tares in a neighbor's field that there are
wicked men in the world; nor is it because a lover of jewels will sell
everything that he has to buy the pearl of greatest price that men
devote everything they have to the kingdom of heaven. Analogies prove
nothing. They clear up relations and often help the reader to
appreciate other arguments. They are valuable when the likeness is
broad and easily traced. They should never be used alone.

These, then, are the principal forms of argument: deduction and
induction; arguments from cause, from sign, and from example. Upon
these men depend when they wish to convince of truth or error.

Selection of Material.

In argument the material is selected with reference to its value as
proof. Every particle of matte