This is a poem, described by William Motherwell in his "Minstrelsy Ancient and Modern" (1846) as: "A nursery tale of Galloway [a district in the Scottish borders], and a specimen of . class of compositions of great antiquity, representing the Enemy of man [the devil] in the endeavour to confound some poor mortal with puzzling questions."
In the story, the peat carried by the wee boy was his contribution to the schoolmaster's stock of fuel.