"Sensation is not the conduction of a quality or state of external bodies to consciousness, but the conduction of a quality or state of our nerves to consciousness, excited by an external cause"

Johannes P. Muller's quote offers a profound insight into the nature of sensation and understanding, emphasizing the subjective experience of sensory stimuli. At its core, the quote challenges the simplistic view that experience is merely a direct transmission of the qualities of external objects to our consciousness. Rather, Muller posits that feeling includes an intermediary procedure-- particularly, the nerves' function in conveying info to our awareness.

According to Muller, feeling is not about sending the inherent qualities of external items (like the color, shape, or texture of a rock) directly to the mind. Rather, it revolves around how external causes or stimuli affect our sensory nerves, which then send this details to our awareness. This difference highlights the subjective nature of perception, recommending that what we perceive is not an unfiltered replication of the external world but a construction formed by the peculiarities of our nervous system.

Muller's point of view foregrounds the active role of the nervous system in shaping our sensory experience. External stimuli may activate nerve actions, but it is the quality or state of these nerves that ultimately forms our conscious experience of those stimuli. For instance, the perception of color does not live in the things but manifests through the interaction between light, the eyes, and the brain's interpretation of that interaction.

This point of view is integral to comprehending why various individuals may view the same stimulus in a different way, influenced by variations in their sensory apparatus. In addition, it hints at the possibility of affective illusions and stresses the intricate processes underpinning sensory experience.

Muller's insight is prescient in foreshadowing later on developments in psychology and neuroscience that examine the intricate methods which understanding is built by the central and peripheral nervous systems. In sum, Muller advocates for a view of sensation that acknowledges the mediating role of the nerves, challenging us to consider the complex, subjective nature of human sensory perception.