Speaking with Songfacts, Midón explained
that "Suddenly" came to him while reading Carlos Castaneda's The Teachings of Don Juan
, which was published in 1968 and is one of the most influential non-Christian spiritual books in recent American history. It's still read widely today; the book's origins are controversial, but Castaneda said that was based on his experiences studying under a Mexican shaman.
The spiritual paradigm expressed in the book is complex (and went on to spawn not only a series of more books but also a rather large spiritual following), but essentially comes down to the notion that reality is multilayered, and we are capable of not only seeing layers beyond our own but also directly influencing them.