A landscape is nothing but a cluster of sensations.

The outward form of a body is simply sensation; and the innermost and most delicate material structure, the last visible elements of a cell, for example, are all, in so far as we observe them with the microscope, nothing but sensation.
This being understood, the question is, why we have just admitted--with the majority of authors--that we cannot really know a single object as it is in itself, and in its own nature, otherwise than by the intermediary of the sensations it provokes in us?
This comes back to saying that we here require explanations on the two following points: why do we admit that we do not really perceive the objects, but only something intermediate between them and us; and why do we call this something intermediate a sensation?
On this second point I will offer, for the time being, one simple remark: we use the term sensation for lack of any other to express the intermediate character of our perception of objects; and this use does not, on our part, imply any hypothesis.

Especially do we leave completely in suspense the question whether sensation is a material phenomenon or a state of being of the mind.

These are questions we will deal with later.

For the present it must be understood that the word sensation is simply a term for the something intermediate between the object and our faculty of cognition.[3] We have, therefore, simply to state why we have admitted that the external perception of objects is produced mediately or by procuration.
There are a few philosophers, and those not of the lowest rank, who have thought that this intermediate character of all perception was so evident that there was no need to insist further upon it.