This paper is a search for the origins and nature of human consciousness. This portion, the first part of two, takes up a signal work of Jung and one of Freud, both published in 1911 and both deriving thinking as the first embodiment of higher mental functions. Thinking and consciousness (and subsequently spirit) are elaborated in terms of the nature and vicissitudes of libido. Jung's less well understood theory regarding a quantitative libido is particularly addressed as are his non-Cartesian ways of reasoning. Also addressed is Jung's turning away in the final analysis from a frankly metaphysical and transcendent position as compared to the pre-Socratic philosophers with whom focused thinking began in the western world. Differentiation is made between mechanistic and energetic field dynamics in how reality is viewed.