A beautiful book on angels:
Henri Marie Bouden - Devotion to the Nine Choirs of Holy Angels
'Before concluding this subject, I am desirous to point out a common but dangerous temptation, which renders almost all our actions either profitless or imperfect: it is that the devil labours to make us be occupied with anything but what we are about. If you are engaged in prayer, he will make you think of some good action you have to perform: when you are performing this action, he will occupy your mind with some other; and thus you are always thinking of something you are not doing, and only give half your thoughts to it. Now each moment has its special blessing; do well whatever you are doing; and that you may do it well, think of nothing else. The moment that is past is no longer yours; the future is not yet come; the present, therefore, is all you have. Here, then, is the devil's stratagem: by getting you not to attend to the present and keeping you always rehearsing, as it were, for the future, he leaves you no moment really your own.'
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