De cogitatione (‘Concerning Thinking’) is a brief work on the governance of one's thoughts, specifically the rejection of evil thoughts against God [lines 1–8] and the regulation of one's intentions [lines 9–29]. The composition belongs among a number of short pieces ‘composed independently by Ælfric and set aside for later (re-)use, being kept in “a book in which short themes, obiter dicta [passing comments], and letters were put on record from time to time as they were composed”’. He wrote De cogitatione between about 998 and 1002, and later used a portion of it in his revision of his homily on the raising of Lazarus (Lazarus II [AH I.3], lines 288–95). There he links prayer for protection from the devil to the promise of remaining unharmed for those who reject the evil thoughts meant to bring them to despair. That Ælfric thinks about thinking should come as no surprise. For him, spiritual warfare is waged in the interior, and the front lines are drawn in the mind. He does not believe that Satan can compel humans to sin, so Christians lose the battle when they capitulate to the devil's instigations by taking pleasure in and consenting to evil. So strong is Ælfric's sense of human culpability that he often underscores the necessity for Christians to earn God's conferral of everlasting life as they fight with mind and body to save their souls. This ‘doctrine of merit and reward’ is reflected in De cogitatione's final sentence when he writes that the believer will receive ‘recompense according to his mind's disposition’ (‘þa mede be his modes fadunge’ [line 27]) and that Christ ‘repays everyone according to his action’ (‘agylt ælcum be his dædæ’ [line 29]). The parallelism of thinking and doing establishes thinking as doing, and explains Ælfric's rather labored comparison of good and evil intentions. For believers, the knowledge that God distinguishes between intent and outcome demands of them a striking degree of self-awareness concerning their thoughts and motivations. Such reflexivity accords well with the value Ælfric places generally on introspective rather than rote belief and practice. That value is reflected not least in his preference for exegetical sermons like that into which he incorporated part of De cogitatione and which call all Christians to reflect on and then apply to their lives such theological concepts as those discussed in this work.