The 'Author's Effect of Showcasing' (AES) is the activity of the publishing researchers as authors with which they shape by free will the formal reference stock of their communications cited directly and itemizedly, placing this formal reference stock into the showcase of modern science - consciously or unconsciously. Its fundamental cause is the scientific publication explosion of the past century: the constantly uncitable vast quantity of the relevant and citable literature. This gives rise to the necessity of selection, choice and lifting out in the course of the author's personal referencing practice. This first paper of the study demonstrates the emergence, causes and traces of the AES phenomenon in the journal literature of the natural sciences already in the mature Little Science age, and the continuous existence of the phenomenon ever since. The perception and cognition of the effect is shown on the basis of the relevant findings of the present author's previous, manual fact-finding reference investigations based on autopsy, processing around 27,600 journal communications and reference stocks containing more than 322,000 citations. Finally, a summarizing definition of the effect is given. In the next, second paper, the manifestation of the AES phenomenon will be demonstrated and analyzed in the theoretically most homogeneous domain of the scientific literature.