4325. The activity of the senses in general, or general sensory activity, is divided into voluntary and involuntary. Voluntary sensory activity belongs properly to the cerebrum, but involuntary to the cerebellum. These two forms of general sensory activity are combined in the human being; yet they are distinct and separate. The fibres which issue from the cerebrum establish voluntary sensory activity in general, and the fibres which do so from the cerebellum establish involuntary. The fibres from these two sources combine together in the two appendages called the medulla oblongata and the medulla spinalis, and through these pass into the body and there shape its members, viscera, and organs. The parts which envelop the body, such as muscles and skin, and also the sensory organs, for the most part receive fibres from the cerebrum, and through these a person has sensory awareness and also movement controlled by his conscious will. But the parts which are contained within that outer envelopment or enclosure and which are called the viscera of the body receive fibres from the cerebellum, and therefore a person does not experience any feeling in these, and they are not subject to his conscious will. This shows something of what sensory activity in general is, that is, what general sensory activity is, both voluntary and involuntary. In addition it should be recognized that the general whole must exist first before any individual part can do so; that no individual part can possibly come into being and be kept in being without the general whole, and indeed that it is kept in being within this; and that every individual part is conditioned by the nature and state of the general whole. The same applies to sensory activity in the human being, and also to movements.