There are moments when Chaucer's writings can sound peculiarly modern. One such moment comes when a knight's extravagantly lyrical description of a woman he has loved provokes a sceptical reaction from the narrator of the Book of the Duchess. The narrator observes that he can well believe that the woman seemed the very loveliest to behold, to anyone who looked at her with the knight's eyes (‘Whoso had loked hir with your eyen’, BD 1051). That detachment and relativism in thinking about personal attraction has a twenty-first-century flavour.

On the other hand, there is much in Chaucer that will seem alien, at least to many in the modern Western world. Sexual intercourse between unattached consenting adults is by no means now widely taken to be a ‘sin’ of fornication, but the Wife of Bath recalls that amorous escapades are reckoned sinful (‘Allas, allas! That evere love was synne!’, III 614). Stranger still to modern sensibilities, medieval Christian doctrine pronounced sexual intercourse even between married partners to be sinful under various circumstances, as we shall see in detail later. A hint of this is found in the Miller's Tale, when the student Nicholas is developing his crafty plan to bed a carpenter's wife under cover of the hypothetical approach of a new Noah's Flood. Nicholas coolly warns the carpenter that on the auspicious night of the projected flood he must sleep well away from his wife so that ‘bitwixe yow shal be no synne, / Namoore in lookyng than ther shal in deede’ (I 3590–1). ‘No synne’ evidently means no sex – not even sexual thoughts prompted by ‘looking’.

There are both general and specific resonances from Christian doctrine here. The general presumption was that marital (let alone extra-marital) intercourse was always, as it were, on the verge of sinfulness by reason of its satisfaction of clamorous physical urges, even when a man and wife engaged in it for reasons approved by the Church. Sex was held to be incongruous with prayerfulness, because ‘the presence of the Holy Spirit is not given at the time when conjugal acts are undertaken’. The specific presumption is that abstinence from sex would be strongly advisable in a context where danger is looming.