Isaac of Nineveh, or Isaac the Syrian, a 7thcentury solitary belonging to the Church of the East, became a point of reference for the whole orthodox tradition. The central value of humility in his writings has recently been pointed out by scholars. This paper analyses Isaac’s conception of pride, the attitude opposite to humility, through a close reading of passages selected from his ‘First Part’ and from his recently rediscovered ‘Second Part’. A particular emphasis is placed on the Syriac text and on the specific vocabulary Isaac employs. The paper also aims, through an analysis of Isaac’s quotations of earlier monastic writings, to identify the background and sources of his conceptions, especially the ‘Apophthegmata Patrum’ and Palladius’ ‘Historia Lausiaca’, examined in the Syriac version of ‘Enanisho‘, a contemporary of Isaac. It will be argued that pride can be understood as a flight of the individual from negativity: looking only for spiritual fulfilment, the person forgets the necessary relationship with the painful aspects of life. This can also lead, in Isaac’s descriptions, to a loss of one’s mental stability and of the sense of reality, and can only be opposed by a positive limitation of desire which leads the person back to his real status of human creature.