Meaning of 然 in conjunctions and other grammatical words?

Question

Here are a few grammatical words that use 然 according to jisho.org: > * 然し（しかし） * however; but * 然して（そして） * and; and then; thus; and now; and finally * 然うして（そうして） * and; like that​ * 然も（しかも） * (1) moreover; furthermore​ * (2) nevertheless; and yet​ * 然も（さも） * (1) really; extremely​ * (2) in that way​ (Archaism) * 然う（そう） * (1) in that way; thus; such * (2) so (agreement) * (3) so? (doubt) * 然るべき（しかるべき） * proper; appropriate; due; suitable According to jisho.org, the meanings of 然 are: > sort of thing, so, if so, in that case, well The relationship between all these different words and 然 is vague and hard to understand. Can you offer a logical analysis of why/how 然 is used in such expressions?

Answer 1

My first instinct it that it stems from Classical Japanese. These all seem to be related to verbal forms and in Classical Japanese, there were more irregular verbs.