One must be cautious about critiquing the sophistication of the past because the present shall be come the past. The following remarks on Priestley's adherence to the phlogiston theory are appropriate.

"Priestley's notion of original research, which seems quite foreign to our present ideas, may be excused, perhaps justified, by the state of the science in his day."

Roscoe and Schorlemmer, Treatise on Chemistry, Vol. I, 1905, pg. 19.