The lure of the thing is unexplainable.
"My Attainment of the Pole"
Frederick A. Cook
All this was a decided change from driving a few hours daily in a lightly loaded wagon, but what at first had appeared an almost unexplainable liking for the constant effort had grown upon him.
"A Prairie Courtship"
Harold Bindloss
Now, at last, we shall be together, and that terrible, unexplainable past will be buried for ever....
"Doom of the House of Duryea"
Earl Peirce