The document discusses several key concepts in architectural theory and design. It defines architecture as combining the Greek words "archi" meaning first or original and "tect" meaning the ability to put things together. Architectural theory is described as a collection of organized thoughts and ideas that evolve over time. The essence of architecture is said to be the process of making the invisible pulses of life visible through physical form. Several architectural systems and elements involved in designing space, structure, enclosure, circulation, and context compatibility are outlined. [END SUMMARY]