New Gem | No More Learning

and so are sympathies; and so are
signs; and the three combined make one mystery to which humanity has not
yet found the key.

Word:

no one

Question:

Why has humanity not yet found the key to the mystery formed by the combination of sympathies, signs, and an unknown factor?

Answer (optional):

Humanity has not yet found the key to the mystery formed by the combination of sympathies, signs, and an unknown factor.