First sentence is incorrect. We are only entitled to FACTS. and many think they know the truth but have not walked the walk to certainty. One does get nearer to the truth with science but even its conclusions have to change when the facts change.

At that time period, although to rudiments of the scientific method were there the scientific method itself had not yet been firmly established in his time period. It was a lot harder to determine facts from opinion without it having been solidly established.

So, at the time, his statement was more true then, than it is today.