Complex sentence: The philosopher Immanuel Kant said that humans are incapable of direct, unmediated knowledge of the world--all experience is mediated through the human mind, which universally structures experience (knowledge) according to the person's perceptions of time and space.
Split into simpler sentences: The philosopher Immanuel Kant said that human beings are incapable of direct, unmediated knowledge of the world. All experience is mediated through the human mind, which universally structures perceptions according to the person's perceptions of time and space.