I should have known it, but didn't:
"indigo - 1555, from Sp. indico, Port. endego, and Du. (via
Port.) indigo, all from L. indicum, from Gk. indikon, lit.
"Indian substance," neut. of indikos "Indian," from India (see
India). "

I should have known it, but didn't

If we'd've thought about everthang we could have known if we'd've thought about it we wouldn't've had time to look everthang up to find out that we were right.

R.D. Laing, Knots (1970)

There is something I don’t know that I am supposed to know....

http://www.stmarys.ties.k12.mn.us/Hopkins/HTMLPres/sld008.htm

On knowing - albeit people rather than facts, I do like this:

"I don't know half of you half as well as I should like; and I like less that half of you half as well as you deserve." - Bilbo Baggins

dxb.

strange coincidence, I found this strange word twice in the last hours.
The other one was from a letter of Gustave Flaubert to his sister Caroline (1843), proposing a "mathematical"problem , making a joke about mathematics nonsense-ness


L'age du capitaine (Gustave Flaubert, Lettre à sa soeur Caroline, 1843)
Puisque tu fais de la géométrie et de la trigonométrie, je vais te donner un problème: un navire est en mer, il est parti de Boston chargé d'indigo, il jauge deux cents tonneaux, fait voile vers Le Havre, le grand mât est cassé, il y a un mousse sur le gaillard d'avant, les passagers sont au nombre de douze, le vent souffle NNE, l'horloge marque trois heures un quart d'après-midi, on est au mois de mai...
On demande l'âge du capitaine.

Since tu are studying geometry and trigonometry, I am going to give you a problem: a ship is in the sea, it left Boston with a load of indigo, the load is two hundreds barrels, it is going to Le Havre, the big mast is broken, there is moss on the prow scaffolding (??), the passengers are twelve, the wind comes from NNE, it is 15.15 in the afternoon, it is may...
Which is the age of the captain?

Dear emanuela: I am completely ignorant of mathematics. But what little I do know
suggests very strongly to me that all of the information given is irrelevant towards
determining the age of the captain. It is similar to old joke about what time is it
when one Ford passes another Ford. The answer to that one is ten past ten.
(tin past tin, a sneer at the allegedly flimsy construction of the vehicles.)

(tin past tin, a sneer at the allegedly flimsy construction of the vehicles.)

FORD

F.ound O.n the R.oad D.ead

or

F.ixed O.r R.epaired D.aily

(been hearin' those since I was a kid...some things never change! )