The fact that an opinion has been widely held is no evidence whatever that it is not utterly absurd; indeed in view of the silliness of the majority of mankind, a widespread belief is more likely to be foolish than sensible.
Sometimes I've believed as many as six impossible things before breakfast.
Is there life before death?
What can you say about a society that says that God is dead and Elvis is alive?
The faceless, eyeless armed man above me kept his gun very level.
Any transition serious enough to alter your definition of self will require not just small adjustments in your way of living and thinking but a full-on metamorphosis.
The radical of one century is the conservative of the next. The radical invents the views. When he has worn them out the conservative adopts them.