knotty point

See: enigma
References in classic literature ?
And the discussion of a knotty point in the court of conscience.
At first I offered her the same help which I had always found it necessary to confer on the others; I began with unloosing for her each knotty point, but I soon discovered that such help was regarded by my new pupil as degrading; she recoiled from it with a certain proud impatience.
The knotty point was, however, soon decided; and, on the appointed day, the brotherhood marched in great state, displaying sundry banners and mysterious symbols, each man with a little mimic apron before him, from a most cunningly contrived apartment in the garret of the “Bold Dragoon,” an inn kept by one Captain Hollister, to the site of the intended edifice.
said D'Artagnan, "this ought to be the knotty point of the whole thing; they want a pattern of each of the materials.
I maun joost see that the cook's;'s dune her duty--the creatures are no' capable o' decidin' that knotty point for their ain selves.
This elucidation of a knotty point being received with such marks of approval as to put John Willet into a good humour, he contented himself with repeating to his son his command of silence, and addressing the stranger, said:
His experience on the lock gave him such an acute perception of the enormous difficulty of 'tying up' money with any approach to tightness, and contrariwise of the remarkable ease with which it got loose, that through a series of years he regularly propounded this knotty point to every new insolvent agent and other professional gentleman who passed in and out.
Trot, I tell you what, my dear,' said my aunt, one morning in the Christmas season when I left school: 'as this knotty point is still unsettled, and as we must not make a mistake in our decision if we can help it, I think we had better take a little breathing-time.
It was a knotty point, but I made up my mind that we must risk it and use the expresses.
At first, the Carrier looked about him sometimes, with a smile, or now and then called Dot to peep over his shoulder at his hand, and advise him on some knotty point.
But the young stranger appeared much better disposed to partake of the good cheer, with which he had been so providentially provided, than to take up the cudgels of argument on this, or on any other of the knotty points which are so apt to furnish the lovers of science with the materials of a mental joust.
It is pretty generally known what is the reason of the quarrel, which appears to me to be of a very petty nature and if the officials could only be got to shake hands and let bygones be bygones I am sure the players would only too readily agree to enter the arena and endeavour to decide the knotty point of which is best.