“At any given moment there is an orthodoxy, a body of ideas of which it is assumed that all right-thinking people will accept without question. It is not exactly forbidden to say this, that or the other, but it is "not done" to say it... Anyone who challenges the prevailing orthodoxy finds himself silenced with surprising effectiveness. A genuinely unfashionable opinion is almost never given a fair hearing, either in the popular press or in the high-brow periodicals.”
This three part video series is EXCELLENT.
Many will say: "so what, this is ancient history, what does it matter?", or unfortunately, some even say that they don't care about history.
Part 3 explains why this thinking is wrong