What is prayer?

550 C. M.
What is prayer?

PRAYER is the soul’s sincere desire,
   Utter’d or unexpress’d;
   The motion of a hidden fire
   That trembles in the breast.

2 Prayer is the burden of a sigh,—
   The falling of a tear,—
   The upward glancing of an eye,
   When none but God is near.

3 Prayer is the simplest form of speech
   That infant lips can try;
   Prayer, the sublimest strains that reach
   The Majesty on high.

4 Prayer is the Christian’s vital breath
   The Christian’s native air;
   His watchword at the gates of death,-
   He enters heaven with prayer.

5 Prayer is the contrite sinner’s voice,
   Returning from his ways;
   While angels, in their songs, rejoice,
   And cry,—Behold, he prays!

6 O Thou, by whom we come to God,
   The Life, the Truth, the Way,—
   The path of prayer thyself hast trod:—
   Lord, teach us how to pray!
                          James Montgomery
                          Methodist Episcopal hymnal (1870 edition)

<idle musing>
As I've said before, this guy's biography is inspiring. Oh, and hymnary.org adds two verses, while omitting verse 2:

5 The saints in prayer appear as one,
   in word and deed and mind;
   while with the Father and the Son
   sweet fellowship they find.

6 Nor prayer is made on earth alone:
   the Holy Spirit pleads,
   and Jesus on the eternal throne
   for sinners intercedes.

</idle musing>