dic resources which have that variety and freedom of interaction
which can be organized into true works of art and can give the ancient
mechanical devices themselves a genuine artistic character attainable by
no other means.

The earliest canonic form is the _rondel_ or _rota_ as practised in the
12th century. It is, however, canonic by accident rather than in its
original intention. It consists of a combination of short melodies in
several voices, each melody being sung by each voice in turn. Now it is
obvious that if one voice began alone, instead of all together, and if
when it went on to the second melody the second voice entered with the
first, and so on, the result would be a canon in the unison. Thus the
difference between the crude counterpoint of the rondel and a strict
canon in the unison is a mere question of the point at which the
composition begins, and a 12th century rondel is simply a canon at the
unison begun at the point where all the voices have already entered.
There is some reason to believe that one kind of rondeau practised by
Adam de la Hale was intended to be sung in the true canonic manner of
the modern round; and the wonderful English rota, "Sumer is icumen in,"
shows in the upper four parts the true canonic method, and in its
two-part _pes_ the method in which the parts began together. In these
archaic works the canonic form gives the whole a consistency and
stability contrasting oddly with the dismal warfare between nascent
harmonic principles and ancient anti-harmonic criteria which hopelessly
wrecks them as regards euphony. As soon as harmony became established on
a true artistic basis, the unaccompanied round took the position of a
trivial but refined art-form, with hardly more expressive possibilities
than the triolet in poetry, a form to which its brevity and lightness
renders it fairly comparable. Orlando di Lasso's _Celebrons sans cesse_
is a beautiful example of the 16th century round, which was at that time
little cultivated by serious musicians. In more modern times the
possibilities of the round in its purest form have enormously increased;
and with the aid of elaborate instrumental accompaniments it plays an
important feature in such portions of classical operatic _ensemble_ as
can with dramatic propriety be devoted to expressions of feeling
uninterrupted by dramatic action. In the modern round the first voice
can execute a long and complete melody before the second voice joins in.