The document presents an equation for intelligence proposed by Twain that defines intelligence as the integral of perceptions, senses, actions, logic, and memory over time from an initial time to present. It describes intelligence as being affected by aging and influenced by factors like emotions, language, culture, gender, values, vision, hearing, touch, taste, smell, spatial reasoning, force, repetition, hierarchical patterns, experiences, expectations, sense of self, groups, and object-subject relationships.