“When thinking” is the right answer (the definition of retrospect is “a survey or review of a past course of events or period of time”. So “when thinking “ is most likely the right answer.
Answer:
Cheese was the first food.
In this excerpt, we can read the conclusion of Victor Frankenstein about science: in the 19th century, scientists pursue their studies at any personal or moral cost:
"With a confusion of ideas only to be accounted for by my extreme youth and my want of a guide on such matters, I had retrod the steps of nowledge along the paths of time and exchanged the discoveries of recent inquirers for the dreams of forgotten alchemists. Besides, I had a contempt for the uses of modern natural philosophy. It was very different when the masters of the science sought immortality and power; such views, although futile, were grand; but now the scene was changed. The ambition of the inquirer seemed to limit itself to the annihilation of those visions on which my interest in science was chiefly founded. I was required to exchange chimeras of boundless grandeur for realities of little worth.
Such were my reflections during the first two or three days of my residence at Ingolstadt, which were chiefly spent in becoming acquainted with the localities and the principal residents (..)"
When the objective of the science experiments is only the recognition, the need for making something original and spectacular, to be regarded by other scientists the results could be terrible. For example, the creation of the poor monster of Frankenstein story.
