Indeed, some may be surprised to learn that we are not dealing with one prophet here, but with the traditions of at least three different prophets, from three different historical periods. Scripture scholars identify the first 39 chapters as coming from an eighth-century prophet, Isaiah, a contemporary of Amos and Hosea. They understand chapters 40-55 as coming from roughly 150 years later (during the Babylonian exile). They name this unknown prophet Second Isaiah. The remaining ten chapters come from yet another hundred years later, and reflect issues after resettlement in the land of Judah. Scholars call this prophet Third Isaiah. Differences of style, concerns and historical backgrounds illustrate how it is possible for three distinct identities underlying the title ‘Isaiah’ to emerge.

It may seem questionable to us moderns to have discrepancies between authors and the writings attributed to them. But we must remember that the recording of traditions in the ancient world was very different from modern times. Even if the authors’ identities are lost to us, their message is not. It was because of the quality of their message that their words were handed down under the protection, as it were, of a more famous prophet. The New Testament writers, who cite Isaiah more than 350 times, were most likely unaware of the composite nature of this book. Nevertheless, if we are to understand what the various parts of Isaiah might mean for us today, it is essential to have some sense of the issues underlying the different periods.

The eighth-century Isaiah received his call in a vision in the Jerusalem temple about 740 bc, in which he was overwhelmed by the majesty of God. The words he heard the seraph utter (‘Holy Holy Holy’ – a Hebrew idiom expressing the inexpressible holiness of God) have travelled down the centuries to become the Sanctus we sing at Mass. Isaiah accepted the Lord’s call with ‘Here I am, send me’ (6:8).

A diplomat unerring in judgement, Isaiah was fearless in confronting his king. He was scathing in denouncing gluttony, land greed, and social injustice (5:8-23). His wonderful image of swords beaten into ploughshares and spears into pruning hooks (2:4) has captured the imagination of peace-desiring hearts down through the ages – particularly in an imposing sculpture in the UN gardens in Geneva.

Isaiah did not mince words when he told the society ladies of his time exactly what God thought of them and their empty vanity (3:16-26). Compassion for the broken-hearted never caused him to pander to the mob (22:1-3). In the midst of political turmoil there was only one approach for Isaiah: ‘If you will not believe, you cannot be secure’ (7:9).

Expectation of a future messiah was largely born of dissatisfaction with the current Davidic king. From Isaiah we inherit a ‘messianic trilogy’, three sets of texts we encounter annually in the Christmas liturgies. The most famous of these is ‘The Lord himself will give you a sign – look, the young woman is with child and shall bear a son, and shall name him Emmanuel’ (7:14). ‘The people who walked in darkness have seen a great light’ (9:2), and ‘A shoot shall come out from the stump of Jesse’ (11:1) are the opening lines of the other two. These texts were seen by the early Christians as fulfilled in the birth of Jesus. There are further messianic gems in the other two prophets sheltering under the name of Isaiah.

Although nothing is known of who Second Isaiah was, he probably lived in Babylon during the period of exile for the Jewish people (587-539 bc). His prophecies open with the announcement of Jerusalem’s approaching deliverance from its time of captivity, and the construction of a highway across the desert from Babylon to Jerusalem (40:1-11). ‘Comfort, O comfort my people, says your God; speak tenderly to Jerusalem.’ Handel chose these words to open his great oratorio, the Messiah. And the words which follow, ‘In the wilderness prepare the way of the Lord’, are cited in all four Gospels, reflecting the widespread belief that the beginning of Jesus’ public life marked the inauguration of the end times, the coming of the Messiah.

In Second Isaiah we also find the four ‘Suffering Servant’ poems, which the early Christian community understood as depicting a suffering Messiah. Not surprisingly, these texts feature prominently in the Holy Week liturgy. Other themes include the celebration of God as creator of all, and God tenderly holding us by our right hand, saying: ‘Do not be afraid, for I will help you’ (41:13).

When we come to Third Isaiah we find further riches. His most famous lines (61:1-2) are placed on the lips of Jesus in the Nazareth synagogue, and define his mission (Lk.4:18-19): ‘The Spirit of the Lord is upon me, because he has anointed me to bring good news to the poor. He has sent me to proclaim release to the captives and recovery of sight to the blind, to let the oppressed go free’ (61:1-2).

Although some three centuries later than First Isaiah, this unknown prophet endorses that moral transparency so central to his predecessors. He denounces all sham, asking instead: ‘Is not this the fast that [God] chooses: to loose the bonds of injustice, to undo the thongs of the yoke, to let the oppressed go free, and to break every yoke? Is it not to share your bread with the hungry, and bring the homeless poor into your house?’ (58:6).

It is impossible to appreciate the riches which lie in the book of Isaiah in a short space. Perhaps we might end with those reassuring words so relevant in these times of global recession: ‘When you pass through water, I will be with you; and through rivers, they shall not overwhelm you; when you walk through fire you shall not be burned, and the flame shall not consume you. For I am the Lord your God, the Holy One of Israel, your Saviour. Because you are precious in my sight, and honoured, and I love you, do not be afraid, for I am with you’ (43:2-5).