According to Polish tradition, it was said that animals had the ability to talk like humans on Christmas Eve, but only to those pure in spirit. Here is an interesting exerpt I thought you might enjoy reading from
Reymont's "The Peasants" (Chłopi).
Meanwhile Vitek, having been greatly struck to hear that cattle possessed human speech on Christmas Eve, called Yuzka away quietly, and they went both of them to the cow-house.
Holding each other by the hands, trembling with awe and crossing themselves more than once, they slipped in amongst the cows.
Down they knelt by the side of the largest one, that they looked on as the Mother of the Byre. Out of breath, agitated, with tears in their eyes and dread in their hearts, as if they were in church during the Elevation--they nevertheless were upheld by strong trust and a lively faith. Vitek put his mouth to her ear, and quavered in a low voice:
"Hist, Grey One! Grey One!"
But she only gurgle inaudibly, and went on chewing with a roll of her tongue and a smack of her lips.
"Something strange has come upon her: she answers naught!
Then they knelt by the next cow, and Vitek, who by this time was on the verge of weeping, called earnestly to her:
"Spotted One! Spotted One!"
They both approaced very close to her mouth, and listened, holding their breath; but never, never a word!
"Ah! no doubt we have sinned, so we shall not hear her speak. The answer only such as are sinless; and we are sinners!"
"True, Yuzka, true! we are sinful, we have sinned. O Lord! so it is! Aye, I stole some bits of string from master once. And an old scrap besides.... Yes, and also..." He could go no farther; remorse and repentance for his faults shook the lad with a convulsion of tears and sobs; and Yuzka, following his example, wepr from the bottom of her heart. They cried together, and would not be comforted till they had laid bare before each other all their "manifold sins and offences."
At home, no one remarked their absence, for all were piously singing hymns--not Christmas carols, which it was not deemed proper to strike up until after midnight.
- Vol.2, pp.87-88; Translated from the original Polish by Michael H. Dzierwicki, Reader of English Literature at the University of Cracow