This thesis sets out to explore notions of an inherited memory of light upon the human perceptual interpretation of architectural space. These considerations are based upon literature review and practice exploration which indicate human visual perceptions ability to read the manifestation of form and visual weighting in light and shadow. These concepts are explored through the consideration of painted shadow in work by William Blake, Fra Angelico, the drawn representation of light in architectural design by Peter Zumthor and Vitruvius and installation works which investigate the interstice of passing time and light by Olafur Eliasson and Sian Bowen. Each chapter seeks to build consideration of the momentary impermanence in perception of changing light, based within the bounds of the diurnal sequence. The thesis is written from the point of view that observance of shadow light in coalescence with architectural form, engenders a response to space which is wholly based upon our biological relationship to light. Models in practice are used as measuring devices and tools for drawing attention to the detail of shadow form and the visual weight of light over an extended period. This practice emerged through thesis consideration of the painted depiction of light as a moment in time held static. As such it provided extensive opportunity to study the visual representation of light alongside its associated visual weight as clues and manifests which drive the perceptual appearance of architectural space.