There are many organisms that do not originate from eggs, such as bacteria or fungi; However, affirming that every living organism comes from an egg was in every respect a revolutionary affirmation for the time. A statement made by William Harvey .
"Ex ovo omnia" is what the frontispiece of Exercitationes de generatione animalium (1651) by William Harvey , a seventeenth-century English doctor and in his day a physician to James I of England, announces.
(Not) far-fetched claim
"Egg" is, strictly speaking, a container that contains the fertilized cell, the zygote with which the male genes of a sperm combine with the female genes of the egg .
That also includes humans. For this reason, at a time when a human ovum had not yet been seen, it was at least risky to affirm that everything comes from an egg, and that human beings have an origin similar to that of birds and amphibians.
This is why Harvey was a pioneer, as Philip Ball explains in his book How to Create a Human Being :
The veracity of Harvey’s vision could only be seen as biology acquired the idea of the cell, the "fundamental unit of living organisms." That view is often attributed to Harvey’s compatriot and near contemporary, Robert Hooke, who made the most productive use of the then newly invented microscope in the 1660s and 1670s.
Havey, then, did not observe it as such , but he was the first to suggest that humans and other mammals harbor a kind of "egg" that contains the successor individual; theory criticized by the scientific community of the moment .
Harvey died on June 3, 1657 in London. Nine years later, in 1666, the so-called Great Fire of London devastates the English capital and completely destroys the College of Physicians, in which a large part of his notes and manuscripts were preserved .