"If there is no source of illness, why are there so many sick people?"
It is because they have found lots of excuses to hold themselves in vibrational discord with wellness. They are not letting it in. And when they don't let it in, the absence of it looks like sickness.
And when enough of them do it you say, "Oh, there must be a source of sickness. In fact, let's give it a label. Let's call it cancer. Let's call it AIDS. Let's call it all kinds of terrible things, and let's imply that it jumps into people's experience."
And we say it never jumps into anybody's experience. It's just that people learn through trial and error, and through banging around with each other, patterns of thought that don't let [wellbeing] in.