How about an alchemical riddle, could you recognize the true Prima Materia?
Hint: It is to be found everywhere; but if you do not find it in your own house, you will find it nowhere. It is a living substance that can be discovered only in places inhabited by man. It is the only substance from which the Philosopher's Stone can be prepared, and without that substance no genuine silver or gold can be made. In thirty pounds of ordinary mercury, there is usually not more than one pound of the true substance; and a hundred pounds of ordinary sulphur usually contain not more than one pound of that which is useful. It can only be found above the earth, but not below it. It is before everybody's eyes; no one can live without it; everybody uses it; the poor usually possess more of it than the rich; the ignorant esteem it highly, but the learned ones often throw it away. The children play with it in the street, and yet it is invisible. It can be perceived by the sense of feeling, but it cannot be seen with the material eye.
There is an old occult maxim which declares that—" Nothing is concealed from him who knows." No Mason is bound to conceal that which he has never learned in the Lodge. All else he receives as he learns any thing, places his own estimate upon its value, and becomes individually responsible for its use. It must be a matter of conscience, and be weighed in the balance of duty, and every one must abide by the result. If Masonry has lost the Royal Secret, or if it never possessed it, or if it was wrenched away in the very name of Religion little more than a century ago, all the same, it belongs to the Craft as the Heir-apparent of the Old Wisdom. But the time has come when no cable-tow can bind it. It now belongs to Humanity equally with the Mason. To this end has it been preserved throughout the centuries.