Sentence:  ... towards the end of dinner ... there is an hymn sung, varied according to the invention of him that composeth it ... but the subject of it is (always) the praises of Adam and Noah and Abraham; whereof the former two peopled the world, and the last was the Father of the Faithful: concluding ever with a thanksgiving for the <WSD>nativity</WSD> of our Saviour, in whose birth the births of all are only blessed. 
Meaning of the word marked with <WSD> tags:  The birth of Jesus. (from 14th c.)