“So settled, so still, so serene / Completely vegetative, cumcumbive, or potative, non-communicative, and green …” Bonkers.
We must be grateful to our enemies, then, because they help us best engender a serene mind!
It was a kind of serene feeling of connection with something higher.
mid-15c., "clear, calm," from Latin serenus "peaceful, calm, clear" (of weather), figuratively "cheerful, glad, tranquil," of uncertain origin; perhaps from a suffixed variant of PIE *ksero- "dry," source of Greek xeros "dry" (see xerasia). In English, applied to persons since 1630s. Related: Serenely.