No poet has been more wilfully contradictory than John Donne, whose works forge unforgettable connections between extremes of passion and mental energy. From satire to tender elegy, from sacred devotion to lust, he conveys an astonishing range of emotions and poetic moods. Constant in his work, however, is an intensity of feeling and expression and complexity of argument that is as evident in religious meditations such as ''Good Friday 1613. Riding Westward'' as it is in secular love poems such as ''The Sun Rising'' or ''The Flea''. ''The intricacy and subtlety of his imagination are the length and depth of the furrow made by his passion,'' wrote Yeats, pinpointing the unique genius of a poet who combined ardour and intellect in equal measure.