Try to make your mind go completely blank. Too difficult? That’s not surprising, at least according to Lorraine Daston of the Max Planck Institute for the History of Science, Berlin.

“If you can’t achieve this tabula rasa state after a few seconds, then it’s no use persisting: the longer and harder one tries, the more stubbornly cluttered the mind becomes,” she said.

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Daston opened her talk “Seeing Things: A History of Blank Screens” on Tuesday with this thought experiment — or anti-thought experiment, as she called it. Mental blankness does not come naturally, she said. But, despite its difficulty to achieve, she said scientists have long considered this blankness an ideal state of mind because it offers objectivity. Throughout the talk, Daston traced the pursuit of blankness by intellectuals through epistemology, religion and the study of sexual reproduction. She also explored how scientists began to progressively distrust their own senses because of their inability to achieve a blank state of mind and turned to technology to eliminate the misleading effects of human imagination.

She first examined the idea of the “impressionable embryo,” originated by Aristotle, who stated that at conception, male semen contributes form, while female uterine tissue contributes matter. Under Aristotle’s ideal circumstances, she explained, the resulting child is a flawless copy of his father. Daston said this philosophy was extended by some thinkers, such as Voltaire, who believed that the contents of the mother’s imagination could have physical effects on the embryo.

Other philosophers, she said, took the idea even further, believing that soft matter outside the body, such as clouds, could be molded by the contents of people’s thoughts, or their “animal spirits,” which were thought to be a vapor that coursed through the nerves.

“It was the workings of the imagination and other form-bearing forces that determined the properties of the perfect medium: soft as heated wax or molten metal, hard as the cooled seal or coin that bears the impress of signet ring or mold,” Daston said.

As the turn of the 19th century approached, the theory of maternal imagination waned in popularity, Daston said, and the idea of “projective imagination” took a new technological form: the optical image on a blank screen. Scientists also began to rely on new technologies as they developed, from daguerreotypes to microscopes.

“Only such automatic images could dispel the suspicions of many colleagues that microscopic observations were riddled with illusions and therefore of no use in medicine,” Daston said.

As she closed her talk, Daston discussed the ideal of blankness in its present state, saying that even though the power of imagination has weakened since the Renaissance, when such mystical ideas as the impressionable embryo were perfectly believable, it remains “projective.”

“It is an emission of a hyperactive mind that refuses to be contained by the boundaries of reason and the body,” she said.

Of the approximately 40 attendees, many worked in fields unrelated to epistemology or the history of science.

Steven Deedon, a writer living in New Haven, said he enjoyed Daston’s tracing of objectivity.

“It was a lovely historical example of our persistent belief that we can find a reality that is not shaped by our minds,” he said, laughing.

Others, though, felt Daston did not quite address certain epistemological issues in her talk.

Miriam Posner GRD ’10 said she is doing research into medical visuality in the 20th century and has found historical examples of doctors who embraced objectivity, but distrusted empirical tools, like X-rays.

“She seemed to be saying that scientists were more and more interested in eliminating subjectivity, but there are some cases where the senses were valued more,” she said.

The talk was the last in a lecture series organized by the Humanities Program, called “Scroll, Book, Screen: Means and Meanings.”