INVOCATION is made as follows: your soul, having realised God’s
Presence, will prostrate itself with the utmost reverence,
acknowledging its unworthiness to abide before His Sovereign Majesty;
and yet knowing that He of His Goodness would have you come to Him, you
must ask of Him grace to serve and worship Him in this your meditation.
You may use some such brief and earnest words as those of David: “Cast
me not away from Thy Presence, and take not Thy Holy Spirit from me.”
 “Shew me Thy Ways, O Lord, and teach me Thy paths.”  “Give me
understanding, and I shall keep Thy Law: yea, I shall keep it with my
whole heart.”  “I am Thy servant, O grant me understanding.” 
Dwell too upon the thought of your guardian Angel, and of the Saints
connected with the special mystery you are considering, as the Blessed
Virgin, S. John, the Magdalene, the good thief, etc., if you are
meditating in the Passion, so that you may share in their devout
feelings and intention,–and in the same way with other subjects.
 Ps. li. 11.
 Ps. xxv. 4.
 Ps. cxix. 34.
 Ps. cxix. 125.