position that if a statute required contracts of a certain kind
to be put in writing, and a contract of that kind, but embracing
also a different and distinct matter not touched by the statute,
was made orally, it was wholly void. Such a rule was illogical
and unsound, and in a later decision the same court, forgetting
that it had indorsed it, said so, and said so when it was not
necessary to the decision.[Footnote: Irvine _v._ Stone, 6
Cushing's Reports, 508, 510.] Subsequently, both these cases
having been brought to its attention, it affirmed the latter,
though remarking that "what was there said on this point was not
essential to the decision of that case, and would have been
omitted or modified if Loomis _v._ Newhall had been then
remembered."[Footnote: Rand _v._ Mather, 11 Cushing's
Reports, 1, 5.]

The authority of an opinion as a precedent on any point is always
proportioned to the necessity of determining that point in order
to support the judgment which was rendered. Some judges write
treatises instead of decisions or in addition to decisions.
Whatever goes beyond that which is required to show that the
judgment is the legal conclusion from the ascertained facts is
styled in law language _obiter dictum_. It may be
interesting and even persuasive, but it is not an authoritative
statement of law.

It may grow to be such by adoption in subsequent cases. The
Court of King's Bench in England was called on, at the beginning
of the eighteenth century, to say whether if a man undertook as a
friendly act, and not for pay, to cart another's goods, and did
it carelessly, he was bound to answer for any damage that might