Вилами на воде писано (vilami na vode pisano).
Literally: written with pitchfork on the water.
Meaning: it is unknown how something is going to be in the future.
English equivalents: up in the air; not written in stone.
Probable origins of the proverb:
1) Although in contemporary Russian ‘vily‘ (pl.) means pitchfork it has also another meaning: South Slavic female spirits who live in ponds (sing.: vila; cf. mermaids). They can tell fortune writing what is going to be on the water.
2) Until now in some Russian dialects ‘vily‘ also means circles on the water. While fortune telling stones were thrown in the water. Prediction was based on the form, size of the resulting circles as well as the way they crossed.
3) There was a pagan ritual: a defensive spell against vodyanoy (male water spirit) when Russian peasants drew a cross on the water using a knife or a scythe. The latter were symbols of the god called Perun. Perun was the god of thunder and lightning (cf. Thor, Zeus, Indra, etc.). He was the highest god of the Slavic pantheon.
4) According to another version this saying is a loan translation of a Greek phrase γράφω στο νερό, i.e. to write on the water which has a figurative meaning – to do something useless or meaningless.
Russian Universe 
I love this. So many story angles. Am especially interested to hear about the vily water spirits. It reminded me of the ballet Giselle, which I loved as a child but never quite understood. But Giselle is whisked away to join the Willi (if I’ve spelled that right) who are female spirits of some sort.
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Thank you! The Wilis in this ballet are the vily (вилы) I mentioned in my post. In Slavic folklore they are described as dead maidens who retaliate against those who did wrong to them.
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Thanks for explaining that. It’s interesting that the word вилы makes more sense to me in the Russian original than in the romanized version. Makes me remember that I miss my Russian. I have little occasion to use it. Probably couldn’t string a sentence together these days.
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My pleasure! Unfortunately, we forget languages that we don’t use in our everyday life. That’s why I encourage people who know Russian to write in Russian (here). It’s a little practice but still a practice!
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