The Preface explains
that these Special Psalms are to be sung instead of the ordinary Psalms
on those days; and authorises the use of Special Psalms approved by the
Ordinary on other days.

In using the Book of Psalms as a book of worship we must remember what
was said of the _Intention_ of our minds in respect to parts of the
Services. There are many Psalms which supply us with the best Prayers
in trouble, penitence or any anxiety. But when using them in these
Services our Intention is not Prayer but Praise, and the thought of God
must inspire our devotions.

{45}

It will often help us if we remember that God's Righteousness is
infinite, as well as His Mercy. It is impossible for man in his
present state to reconcile perfect Righteousness and perfect Mercy: for
Righteousness will have nothing to do with sin, while Mercy forgives
it. These two characteristics of God are revealed to us through Christ
in Whom Righteousness and Peace are united; cf. Ps. lxxxv.

The Psalms, composed by various people at different times, very
frequently are the utterances of men in trouble: and they often sketch
the thoughts or actions of the Ideal Man, in one or other of the four
characters which answer to God's Righteousness and God's Mercy. For,
in response to God's Righteousness, man must be (1) perfectly
_penitent_, and (2) in imitation of God, must _detest sin_: in
imitation of God, (3) he must be perfectly _forgiving_, and in response
to God's mercy, (4) he must have _trust and peace_. The Psalmists
exhibit human nature at its best, but it is human nature all the
time--human nature finding God and associating itself with the Ideal
Man.

Thus the Psalms often rise to the conception of the Messiah; and, even
when that is not their thought, they proceed from other thoughts to
Rest in God and Praise of His Holy Name.

The most difficult Psalms for worship are those which regard sin with
horror, but express the horror without mercy. Man is unable to hold
the two qualities of Righteousness and Mercy simultaneously. We find
it difficult in these days to detest sin because we are learning the
quality of mercy.

{46}

Much of the poetic force of these songs depends on the local incidents
of Israel's history and the scenery of Jerusalem and the Holy Land.
While we use the words, we must also use our imaginations to transfer
the great thoughts to our own experience: for those local colours are
the clothing of thoughts whic