In one of his earlier works, the Lectures on Romans, Martin Luther drew on insights from Augustine to introduce to theology an extraordinary image for understanding the experience of being a sinner. ‘Scripture’, Luther tells us, ‘describes man as so curved in upon himself that he uses not only physical but even spiritual goods for his own purposes and in all things seeks only himself’ (Luther’s Works, vol. 25, p. 345, see also pp. 291-92). What Luther means is (i) that despite our best efforts to get beyond ourselves, to love and serve others to the best of our ability, human beings find it impossible to escape the gravity well of self-interest, and (ii) we are often unconscious of this fact, even as it in fact drives our behavior. Luther quotes Jeremiah 17:9: ‘The heart is deceitful above all things, and desperately corrupt – who can understand it?’

The particular power of the image of the human heart as ‘curved in on itself’ (incurvatus in se) is the way it diagnoses a disturbing contrast between our self-perception and the reality of our ways in the world. Thus the parent who discovers that her desire for her children to flourish and succeed is hopelessly enmired in her own needs and insecurities; or the man who thinks of himself as a loving and dutiful family member but whose first guilty thought upon hearing of an elderly relative’s illness is about what he might stand to inherit; or the martyr in T.S. Eliot’s Murder in the Cathedral, who finds that, deep down, his willingness to by die for his faith is little more than a dramatic act of self-congratulation, an effort to prove his own piety to God and to others. First and foremost, then, the statement that the heart is ‘curved in on itself’ is a sobering assessment of the unconscious self-interest and parasitism that lurks underneath so much human love. In this it is a principle whose truth only really becomes clear through painful and disillusioning experience.

In describing human nature in this way, Luther was especially concerned for the way this principle plays out in religious life: the ways that we think we are humbly serving God in prayer, in service, and in ministry to others, but in fact are trying to prove something to God, or to perform our ‘Christian identity’ in the eyes of our neighbors, like the Pharisee in the parable in Luke 18:9-14 who thanks God for his own piety. As in the parable, the only meaningful response to recognition of our ‘incurvation’ is that of the tax collector, who ‘would not even look up to heaven, but was beating his breast and saying ‘God, be merciful to me, a sinner!’


We hope the following guide will explain how certain technical terms are used on the Mockingbird site.

None of these definitions are, or could possibly be, comprehensive. Hundreds of books have been written on each. We are aiming, instead, via a few broad strokes, to give a sense of how the terms are being used. It should be noted that these terms are sometimes used as shorthand for their philosophical implications, or centrifugal outworkings.

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