Let’s borrow from your post.
Thank you for you answers. They are always so enlightening and helpful
That means that “There are enlightening and helpful posts here.” That is the same as saying “There are enlightening, helpful posts.”
The comma means that both adjectives apply equally to the noun. They are enlightening AND they are helpful. The adjectives carry equal importance and they can come in either order.
You don’t need the comma if the order of adjectives would automatically make one come first: A big red ball. A brown wooden box.
But “He is a kind, sweet man” = “He is a sweet, kind man.”
I always hate to say this, but it’s just the way we do things in English. When the adjectives appear before the noun, we don’t usually use “and”, but in some rare cases it’s optional to do it. When the adjectives are in the predicate of the sentence, they can have “and” between them.
A long time ago, there were two characters on a comedy show who were called “The Wild and Crazy Guys”. They were supposed to be from Czechoslovakia, and their mistake of putting “and” between their adjectives before a noun was part of what made them funny.
Doesn’t the rule say when you have more than one adjective that you have to use “and”, are you saying if you have just two adjectives before a noun you don’t? -Belles
Normally we don’t put “and” between the two adjectives before a noun, because it usually sounds like a foreigner’s speech if someone does that. Sometimes it can sound comical.
Barb’s explanation is correct, so there is not much to add to it.
Nessie, when the standard order of adjectives works for the adjectives, then you don’t need the comma. However, when you have two adjectives that would occupy the same place in that order, use the comma.