“I mean, maybe you just want to see how it all turns out. Maybe it’s all part of a great big ineffable plan. All of it. You, me, him, everything. Some great big test to see if what you’ve built all works properly, eh? You start thinking: it can’t be a great cosmic game of chess, it has to be just very complicated Solitaire. And don’t bother to answer. If we could understand, we wouldn’t be us. Because it’s all — all –”
INEFFABLE, said the figure feeding the ducks.

Terry Pratchett (1948-2015) English author

Good Omens, 7. “Sunday” (1990) [with Neil Gaiman]
    (Source)

Crowley speculating to Aziraphale about God's motivations in creating a flawed Universe.