Experiments with split-brain monkeys suggest that the perception of space and the perception of object identity may be based on anatomically distinct brain mechanisms. This paper examines the visual mechanisms of the brain, proposing that vision involves two parallel processes: an ambient process that determines space around the body, and a focal process that examines details in small areas of space. In vertebrates, there is a detailed topography of body-centered behavioral space projected from the eye to the midbrain. This visual map is integrated with the bisymmetrical motor system, resulting in a correspondence between visual locations and movement goals. The midbrain visual system governs basic vertebrate locomotor behavior. The more recently evolved forebrain visual system focuses almost exclusively on central behavioral space, while cortical motor control is concerned with highly specific actions in the same central area. Anatomy and brain surgery in primates reveal a midbrain visual mechanism involved in ambient space perception. In contrast, focal vision, which relies on the fovea, parafovea, and cortical visual areas, selects areas in the ambient field for detailed inspection. Conjugate eye movements are a direct expression of this attention. The interaction between these two visual analysis mechanisms is a feature of vision in all active animals. The complexity of focal vision in primates is evident at all levels of their visual system and in parts of the motor system that orient vision or control actions directed at specific visual objects. The distinction between vision of space and vision of things or identities is supported by experiments showing that split-brain monkeys can perceive and learn some visual stimuli but not others, suggesting the involvement of two different visual mechanisms.Experiments with split-brain monkeys suggest that the perception of space and the perception of object identity may be based on anatomically distinct brain mechanisms. This paper examines the visual mechanisms of the brain, proposing that vision involves two parallel processes: an ambient process that determines space around the body, and a focal process that examines details in small areas of space. In vertebrates, there is a detailed topography of body-centered behavioral space projected from the eye to the midbrain. This visual map is integrated with the bisymmetrical motor system, resulting in a correspondence between visual locations and movement goals. The midbrain visual system governs basic vertebrate locomotor behavior. The more recently evolved forebrain visual system focuses almost exclusively on central behavioral space, while cortical motor control is concerned with highly specific actions in the same central area. Anatomy and brain surgery in primates reveal a midbrain visual mechanism involved in ambient space perception. In contrast, focal vision, which relies on the fovea, parafovea, and cortical visual areas, selects areas in the ambient field for detailed inspection. Conjugate eye movements are a direct expression of this attention. The interaction between these two visual analysis mechanisms is a feature of vision in all active animals. The complexity of focal vision in primates is evident at all levels of their visual system and in parts of the motor system that orient vision or control actions directed at specific visual objects. The distinction between vision of space and vision of things or identities is supported by experiments showing that split-brain monkeys can perceive and learn some visual stimuli but not others, suggesting the involvement of two different visual mechanisms.