Strange as it may seem the rules of evidence are actually based upon
common sense. The ordinary experience of mankind gave rise to the
rules of evidence, but the difficulty is that the further experience
of civilization is giving rise to new rules which are not consistent
with the old. Nevertheless the present rules when reasonably applied
are fairly good. The question really is whether there should be any at
all.

Accepting the fact that there should be rules they are based on two
principles; the first is that only something which has to do with a
case can be proved and second that it can be proved only in a safe and
reasonable way. It may seem impossible to the lawyer and equally to
the laymen to state the rules of evidence in simple language. But the
principles of common sense will govern in the end, as they have in the
past, notwithstanding they have been hidden under a mass of verbiage,
ancient forms, and obsolete customs.

The theory is that justice wants the highest and best it can obtain,
the court insists on the two principal rules; that evidence must be
the very best that can be obtained and must be brought out in the
safest, clearest, and most authentic manner.

Take, for instance, the rule that conclusions of the witness are not
allowed. If the court considered as evidence that the testimony "the
defendant brought the goods and they were delivered," and the
defendant came on the stand and said, "I did not buy the goods and
they were not delivered," the court would have before it merely two
contrary beliefs or conclusions. It would be a case of "Katy did, Katy
didn't."