The dawn of reason or mental traits in the lower animals explores the mental capacities of lower animals through their consciousness, senses, emotions, and instincts. This scientific work defines the mind as a function of nerve activity, distinguishing between conscious and unconscious mental processes. The author establishes connections between physiology, morphology, and psychology to understand how mental traits evolve in simpler animals. Using examples like jellyfish and actinophryans, the book illustrates how even the most basic organisms show preferences and respond adaptively to their environments. It presents mental action as a continuum beginning with simple sensory responses and moving toward conscious determination, memory, emotions, aesthetic appreciation, parental affection, and reasoning. By examining various species, it aims to trace the origins of mental processes and highlight the gradual emergence of consciousness. The work is written to be accessible to general readers, offering a nuanced and foundational approach to comparative psychology and animal cognition, emphasizing that the roots of mental traits are found far down the evolutionary scale.