We All Know Our ABC's,

but how about the X in our XYZ's?

lets go back in time where there were no letter X's like the use nowadays in words like X-rays and Xylophones, here are some examples of the use X, above, the Lu Lu Alphabet (1867) by Pamela Atkins Colman — Source.

The "Union" Alphabet for Children (1862) — Source.

Nonsense Books (1888) by Edward Lear — Source.

Footsteps on the Road to Learning, or, The Alphabet in Rhyme (1849) — Source.

the Comic Alphabet (1847) by Percy Cruikshank — Source.

and perhaps the most obscure X of them all, What Socrates Said - source, Xanthippe, the supposedly “fiery” wife of Socrates, often shown in a rage pouring a chamber pot over her husband's head, which — according to legend — the philosopher accepted with a simple “After thunder comes the rain”, all I can say is thank goodness for X-rays and Xylophones!