Embryological questions about the origins of life and the nature of becoming are among the most profound questions that human beings have asked, in all cultures and across the millennia. The history of embryological thinking encompasses the long history of religions, philosophies, and cultures, yet the history of the science of embryology first emerged in eighteenth-century Europe. This scientific discipline was founded on the observation that living organisms do not simply exist once and for all but come into being and continue to change throughout their lives.Becoming is a process whose fleeting essence permanently eludes observation and representation. It only becomes an object of scientific inquiry to the extent that it is analyzable, measurable, and depictable. Understanding development and fixing it in the image is a cognitive and perceptual struggle for the ephemeral “in between,” the “not yet” or “no longer” of a process that is regarded as continuous – so as to make that which has just ended, that which proceeds apace or begins anew comprehensible, graphic, and intelligible both in and with the image.This chapter relates the history of embryology – by way of its central milestones and from its beginnings in the eighteenth century through to modern developmental embryology – as a story of seeing, of media and techniques of visualization and forms of representation, but also as a story of preparing and experimenting with model organisms.