icent churches were built under Constantine the Emperor, and
then it came to pass that choirs were instituted definitely by the
Council of Laodicea, A.D. 367. For two centuries the music of the
Church deteriorated. In the Sixth Century Gregory the Great
instituted many reforms, so that the credit of reviving real
congregational singing belonged to him. (See GREGORIAN MUSIC.) The
{142} connection of religion with music is shown by the fact that
nearly every great revival of religion has been accompanied by a
great outburst of song. Beginning with the Reformation, the form
of hymn, called _chorale_, originated in the reformed Church of
Germany and largely with Martin Luther. The most popular part in
congregational singing was the singing of hymns and there have been
three successive styles in hymn-tunes. The first was the diatonic;
the second the florid (from 1730 to 1840), and the third the modern
style (from 1840 to the present time). This modern style is in some
respects a return to the old style of the Sixteenth and Seventeenth
Centuries, with this distinction, that the harmonies instead of
being pure diatonic are more chromatic and less plain. (See MUSIC,
also ORGANS.)

Hypothetical Form.--(See BAPTISM, CONDITIONAL.)

I

Ichthus.--The Greek word for FISH (which see).

I. H. S.--The first three letters of the Greek word for JESUS, and
equivalent to the English letters J. E. S. They are largely used
in Church decorations as symbols of the Holy Name.

Immersion.--The dipping into the water of recipients of Holy
Baptism. For the relative importance of _Immersion_ and _Affusion_,
see article on AFFUSION.

Immovable Feasts.--Those Feasts of the Church which always occur on
the same date such as {143} Christmas Day, Feast of the Epiphany,
etc. As some of the Feasts, such as Ascension Day, Whitsun Day,
etc., are movable depending on the time Easter is kept. Tables and
Rules for the Movable and Immovable Feasts are set forth in the
Prayer Book for convenience and to avoid confusion. (See CHRISTIAN
YEAR, also FEASTS AND GOSPEL.)

Imposition of Hands.--A technical term for the _Laying on of Hands_
by the Bishop in Confirmation. Wheatley on the Prayer Book remarks:
"This is one of the most ancient ceremonies in the world. It has
always been used to determine the blessing pronounced to those
particular persons on whom the hands are laid, and to signify that
the persons, who thus lay on their hands, act and bless