I can not understand this ``then the history of science cannot be understood as an endless succession of scientists carrying out their work ``. please help

Heinrich Feyermahn, in insisting that Galileo did not fully uphold the tenets of scientific rationalism, does not implicate the Italian astronomer, but rather the very edifice of Western thought. For if Galileo is the purported exemplar of rational thinking, and yet is lacking, then the history of science cannot be understood as an endless succession of scientists carrying out their work free of all-too-human biases. Thus, Feyermahn admonishes, in faithfully chronicling the sweep of science in the last 300 years, historiographers would be remiss not to include the human foibles that were part of even the most ostensibly Apollonian endeavors.

I can not understand this ``then the history of science cannot be understood as an endless succession of scientists carrying out their work ``. please help