Recollection is a monastic term and refers to a process used in contemplative prayer. In modern usage the word “recollection” refers to using the memory to bring back to mind some experience, thought or emotion. In the pre-modern (medieval) monastic use of the term, however, it meant something else.
In short, recollection at that time referred to the process of collecting scattered thoughts. Thus it is related to the current term “Centering Prayer”. When practicing contemplative prayer in silence and solitude a person will usually experience times of scattered thoughts. Especially when first entering silence after a time of business or distraction a person will often find their thoughts appearing in fragments and in jumbled groups. The process of “re-collecting” these thoughts constitutes recollection.
Various methods have been advocated. The most common and successful recommendation is to gently return the mind to a central thought or feeling. Thus, often, the practitioner learns to keep coming back to God in one way or another. It can be as simple as just saying to God something like “Oh, God; I’m sorry I keep drifting off from you, help me focus on you”. Many people have found that using a word or phrase whenever scattered thoughts are realized helps to recollect thoughts and allow an inward focus and center. Thus, some will just repeat the name “Jesus”, or a phrase like “my mind is stayed on you”.
Less often the contemplative finds that a pattern of breathing (“I breath you in Lord, and breath out my anxiety”) can aid them in concentration on the presence of God.
One idea is worth a comment: don’t fight with the scattering thought process. To try to “not think of anything” is futile. Realize that God is patient and understanding and persist in the exercise of waiting on the Lord without the added false guilt of believing that God is displeased by your difficulty in being still before Him. Eventually you will succeed and easily become proficient at recollection.
One thing that is very useful is to realize that in contemplative prayer you are trying to go beyond words. So when distracting thoughts keep intruding just return to your heart and send God a feeling. For example, when you realize you have been drifting in thought then “feel” love for God and “send” that love to Him. In the book “The Cloud of Unknowing” the author suggests that you send an “arrow” of love through the “cloud” that is between you and God. Love always gets through.
Lastly it is important to realize that a mind that is still is not empty. To aspire to have “no thought” is a concept from the Eastern Religions, and is not a Christian contemplative concept. The mind is centered on God, not on nothing.