the brain is a part of the central nervous system & the brain can control animal body through the nervous system ->  the brain is a part of the nervous system that controls the body of an animal  a body system is a part of the body / an animal & the nervous system is a kind of body system ->  the nervous system is a part of the body of an animal  the brain is a part of the nervous system that controls the body of an animal & the nervous system is a part of the body of an animal ->  the brain is a part of the nervous system that can control the nervous system  an organ is a part of a body system & if a part of a system can control that system, then that part is a major part of that system ->  if an organ in a body system can control that body system, then that organ is a major organ in that body system  the brain is a part of the nervous system that can control the nervous system & if an organ in a body system can control that body system, then that organ is a major organ in that body system -> the brain is a major organ in the nervous system