Takeo Doi, mainly from a perspective of psychoanalysis, defined the concept of amae as follows: Psychological activities (emotions) seeking mothers after when infants have experienced some degree of mental development and been aware that mothers and themselves were different beings. However, Takeo Doi did not research the etymology of amae nor the rationality of its definition from a linguistic point of view. To address this gap, this study looked at the modern Japanese verb amaeru and the adjective amai corresponding to amae. Furthermore, major etymological lexicons were studied (referring to Kojiki, Nihon Shoki and other classical records) and combined with phonology, phonetics, and early childhood psychology research. The following results were obtained: amae is derived from the "baby's desire for its mother's sweet milk" and "human beings' praise for beautiful things such as God and the gods' laments". This leads to the idea of "the infant's pursuit of a mother who can give her own sweet milk", thereby circumventing the rationality of Takeo Doi's definition of
amae.