Question about Beethoven?

How did he know how to write music in such a way that relates to the feelings we feel? For example, how did he make the song "Moonlight Sonata" how in the world did he make it sound spooky and like the night exactly when he never even heard what sounds like that??? Like could he (for example) play a major chord and identify it as bright and happy and identify minor chords / scales as sad and spooky though he can't hear them? Thanks (: