бытие - отгл.сущ. от быть (be)
быть - be
Old English beon, beom, bion "be, exist, come to be, become, happen," from Proto-Germanic *biju- "I am, I will be." This "b-root" is from PIE root *bheue- "to be, exist, grow, come into being," and in addition to the words in English it yielded German present first and second person singular (bin, bist, from Old High German bim "I am," bist "thou art"), Latin perfective tenses of esse (fui "I was," etc.), Old Church Slavonic byti "be," Greek phu- "become," Old Irish bi'u "I am," Lithuanian bu'ti "to be," Russian byt' "to be," etc. It also is behind Sanskrit bhavah "becoming," bhavati "becomes, happens," bhumih "earth, world."
природа - physis
"nature," from phyein "to bring forth, produce, make to grow" (related to phyton "growth, plant," phyle "tribe, race," phyma "a growth, tumor") from PIE root *bheue- "to be exist, grow" (see be). Spelling with ph- attested from late 14c. (see ph). As a noun, "medicine that acts as a laxative," 1610s. The verb meaning "to dose with medicine" is attested from late 14c.
природа - nature
late 13c., "restorative powers of the body, bodily processes; powers of growth;" from Old French nature "nature, being, principle of life; character, essence," from Latin natura "course of things; natural character, constitution, quality; the universe," literally "birth," from natus "born," past participle of nasci "to be born," from PIE root *gene- "give birth, beget."
т.е. природа это не космос, а то, что рождает его или из чего космос возникает-вырастает как дерево или восходит как солнце
b < ph (быти = фити = пити)
стало быть, бытие = природа = дающее существование как со-бытие = рождающее сущее, но само не сущее (полный аналог кит. Дао: поэтому Гераклит, Лао Цзы и Хайдеггер в одном ряду)
а от со-бытий процесс становления (актуализация потенциала сущности), т.е. время