The fancy came to me that the old priest was smiling

[Nonverbis]

It was after sunset; but the window-panes of the houses that looked to the west reflected the tawny gold of a great bank of clouds. Nannie received us in the hall; and, as it would have been unseemly to have shouted at her, my aunt shook hands with her for all. The old woman pointed upwards interrogatively and, on my aunt’s nodding, proceeded to toil up the narrow staircase before us, her bowed head being scarcely above the level of the banister-rail. At the first landing she stopped and beckoned us forward encouragingly towards the open door of the dead-room. My aunt went in and the old woman, seeing that I hesitated to enter, began to beckon to me again repeatedly with her hand.

I went in on tiptoe. The room through the lace end of the blind was suffused with dusky golden light amid which the candles looked like pale thin flames. He had been coffined. Nannie gave the lead and we three knelt down at the foot of the bed. I pretended to pray but I could not gather my thoughts because the old woman’s mutterings distracted me. I noticed how clumsily her skirt was hooked at the back and how the heels of her cloth boots were trodden down all to one side. The fancy came to me that the old priest was smiling as he lay there in his coffin.

But no. When we rose and went up to the head of the bed I saw that he was not smiling. There he lay, solemn and copious, vested as for the altar, his large hands loosely retaining a chalice. His face was very truculent, grey and massive, with black cavernous nostrils and circled
by a scanty white fur. There was a heavy odour in the room—the flowers.

Source: Dubliners by James Joyce

Could you tell me why "the fancy", that is why the definite article is used here?

 

[jutfrank]

He's referring to it specifically. Read fancy as 'thought'. The thought came to me ...