What does "he who is wrapped in purple robes" mean in "The Ballad of Father Gilligan"?

This section of the poem comes in the final stanza, as Father Gilligan kneels to worship his God who has helped him so much by allowing one of his parishioners to die in peace without the need for him to be at his side. The poem presents us with Father Gilligan, who is overwhelmed by his job and the needs of the people in his parish, and feels exhausted and that his job his hopeless. How can one man possibly hope to meet the needs of all his dying parishioners? As he contemplates this, he falls asleep, and wakes up to find that one of his parishioners has died during his nap. Filled with remorse, he rushes to the house to be told that the man died "as happy as a bird" in spite of his absence. The poem therefore ends with this stanza, which affirms the love that God has for all of his creation, including Father Gilligan, and the way that we can trust in Him when we reach the end of our own strength and resources:

'He Who is wrapped in purple robes,
With planets in His care,
Had pity on the least of things
Asleep upon a chair.'

The figure "wrapped in purple robes" is a conventional depiction of God. We normally associate the colour purple with nobility, and so it is that it is God who has "planets in His care" and is "wrapped in purple robes." But note of course the distinction that is made in this final stanza. Even though God is so powerful and mighty, looking after planets, he still shows love towards "the least of things."

What is the significance of purple robes in Yeats' "The Ballad of Father Gilligan"?

In this poem, Yeats describes a priest who is exhausted because his parishioners "die and die," and thus he has "no rest, nor joy, nor peace."

The priest falls asleep one night after being called to attend upon one of his parishioners, namely a poor man who is ill. When he awakes, the priest discovers that the parishioner has died, and he becomes overwhelmed with guilt. However, when he visits the parishioner's wife, he learns that the man died, in his wife's words, "As merry as a bird." Hearing this, the priest falls to his knees and praises God for sending an angel to look after the parishioner while he, the priest, slept. The priest is overwhelmed with this evidence of God's benevolence.

In the final stanza, referring to God, the priest describes "He who is wrapped in purple robes, / With planets in his care." The color purple symbolizes honor, majesty, and nobility. The fact that God is "wrapped" in this color implies that he is, because of his benevolence, covered completely in honor, majesty, and nobility.