The mind may be reluctant to think properly when thinking is all it is supposed to do; the task can be as paralysing as having to tell a joke or mimic an accent on demand.
The opinion prevailed among advanced minds that it was time that belief should be replaced increasingly by knowledge; belief that did not itself rest on knowledge was superstition, and as such had to be opposed.
In my schoolboy days I had no aversion to slavery. I was not aware there was anything wrong about it. No-one arraigned it in my hearing; the local papers said nothing against it; the local pulpit taught us that God approved it, that it was a holy thing, and that the doubter need only look in the Bible if he wished to settle his mind.