天から降ったか地から湧いたか
(Ten kara futta ka chi kara waita ka;
“Fallen from the sky, or sprung from the earth”)

Definition:

A completely out-of-the-blue occurrence, or something or someone appearing suddenly as if out of nowhere. The image is of something being unexpectedly present as if it had just dropped out of the sky or popped up out of the ground.

Breakdown:

We begin with the noun 天 (ten), “the sky,” followed by directional particle から (kara). The nature of what happens “from” is described by the verb 降る (furu), “to fall,” often used for rain. This verb appears in past tense, conclusive form, and is followed by interrogative particle か (ka). Next we get a parallel phrase beginning with the noun 地 (chi), “ground,” “earth,” similarly marked by the particle から. And again we have a verb, 湧く (waku), “to come forth,” generally referring to an outflow or welling-up of water. This verb also appears in past tense, conclusive form, and again is followed by the interrogative particle. In cases like this the paired kas serve a more rhetorical function: they don’t so much ask “A? Or B?” as they declare “whether A or B.”

Notes:

It seems that this phrase has been translated into English in the past, somewhat dramatically, using phrases like “vision” or “apparition” to emphasize its mysterious aspect. Contrast the physicality of the water imagery with, for example, the more explicitly supernatural 神出鬼没.

Example sentence:

「研究で困る度に、行き詰まったと認めた瞬間、足音も立てずにあの図書員が天から降ったか地から湧いたか、そばに現れて手伝ってくれる」

(“Kenkyuu de komaru tabi ni, ikidzumatta no mitometa shunkan, ashioto mo tatezu ni ano toshoin ga ten kara futta ka chi kara waita ka, soba ni arawarete tetsudatte kureru.”)

[“Whenever I’m having trouble with my research, at exactly the moment when I admit to myself that I’m stuck, that librarian appears at my side as if out of thin air, without even the sound of a footstep, and helps me out.”]