greek words a.m.a.p ("exist")

"exist' and "existence".  two seemingly english words, finely embedded in the english dictionary.  But has it ever occured to you that they come from the Greek verb "esti"?  (esti = be)  Esti is much more ancient than the latin verb "essere" with the same meaning.  The prefix ex is also greek.  I site some ancient greek verbs which sound like exist: "existamai", "existimi" Meanings vary, but etymology is not based on strict and direct meaning origin, but rather on geographical and cultural variations.  (no source, blogger's opinion)