What does "dieu scait tout" mean in english?

Question

i recently bought a very rare, very old book and on this inside cover i found a that a previous owner (from the victorian era, im guessing) included their family crest with these words, and i am curious as to what they mean. i have studied latin and from the roots of the words i could make out something about god and "all" or "total", but that is a literal meaning.

the book was once owned by Thomas Herbert Lewin, and it is his crest, i found, that bears these words.

Answer 1

It's definitely French.  Dieu is "God" and tout is "all", but I don't know what scait means.  I wonder if it could mean something like "God Keep Us All"  or "God Be With Us All"?

Answer 2

God knows all

I think scait is probably sait

Answer 3

Dieu scait tout means God knows everything.  Scait formerly = sait now.  This is not a misspelling, just renaissance French.