The later chapters of the book try to synthesize many of the points made earlier about the visual system into a unified framework, although Crick frequently notes the many exceptions to his assumptions and the clumsiness of many of his attempts at synthesis. Also, here he takes the opportunity to make suggestions for further experiments that could provide empirical basis for further understanding about human consciousness and includes a brief addendum on several topics he purposefully glossed over, like free will. Overall, the message Crick repeats as the main purpose of writing the "Astonishing Hypothesis" is to break the scientific community's reluctance to give consciousness a thorough and scientifically-grounded investigation, and to encourage others such as philosophers to address the issues of consciousness in a way that takes account of neuroscientific discoveries.