Both Uses

spontaneous
in
The Phantom of the Opera
(Auto-generated)

But we spontaneously seized each other's hand.†
Chpt 6 *

spontaneously = happening in a natural manner without planning or external force
I quote these lines, which are particularly interesting because they describe the very simple manner in which the famous incident of the twenty-thousand francs was closed: "As for O. G., some of whose curious tricks I have related in the first part of my Memoirs, I will only say that he redeemed by one spontaneous fine action all the worry which he had caused my dear friend and partner and, I am bound to say, myself.†
Chpt Epil.

spontaneous = behaving in an instinctive, uninhibited manner OR happening naturally (without planning or external force)

Definitions:

(1) (spontaneous)
happening naturally, suddenly, or without outside planning or action
(2) (meaning too rare to warrant focus)