The poem When I Set Out for Lyonnesse is about the poet’s journey to an imaginary country by the name of Lyonnesse and his transformation after returning back. In order to understand the poem, we must first understand its background.
It is believed that Lyonnesse was a country that according to Arthurian legend (King Authur) was near Cornwall (a country near England) before sinking beneath the sea. Hence the poet imagines going to that city.
The poet, who was an architect, went to supervise the construction of a Church in Cornwall. There he met Emma who later on became his wife. Thus the whole poem describes how the poet felt after meeting her.
The poem is divided into three stanzas. We will discuss them line by line and also understand the meanings of difficult words.
In the first stanza, the poet says that when he set out for Lyonnesse (Cornwall, in real) which was a hundred miles away, there was rime (frost i.e. small ice crystals) on the spray (leaves and branches).
The line gives an insight into the climate. It was winter season and thus chilling cold was everywhere. In poetry, winter symbolizes doom or sorrow or darkness. Hence the poet seems to be hopeless.
He feels lonely and the starlight (twinkling stars, the light of which is very less) is his only hope. According to him, the twinkling stars lit (takes away) his lonesomeness (loneliness).
The poet repeats the first two lines. According to him, all this happened when he set out for Lyonnesse which was a hundred miles away from his home. The first stanza symbolizes hopelessness and a quest for something.
In the second stanza, the poet wonders what would bechance (happen) at Lyonnesse when he will sojourn (stay temporarily) there. The lines depict that the poet is quite curious and excited about the visit.
He feels that neither prophet (here it means priest) can durst declare (dare to tell) nor the wisest witch (future teller) can guess.
Again, the first two lines of this stanza are repeated. According to him, he doesn’t know what will happen at Lyonnesse when he will stay there.
The second stanza describes the poet’s curiosity. He is thinking that something great and memorable will happen at Lyonnesse.
In the third stanza, the poet returns from Lyonnesse. He does not tell what exactly happened there. However according to him when he returned back from Lyonnesse, all the people marked (found) that there was magic in his eyes i.e. his eyes were shining.
They found that the radiance (glow and shine) in his eyes is rare and fathomless (deep and profound). Thus the poet seems to have achieved something which he was questing for. His hope is fulfilled. He has gotten something that has transformed him. It was Emma, his soon-to-be wife.
Again the poet repeats the first two lines of this stanza. According to him, all this happened when he returned back from Lyonesse with magic in his eyes.