Observe that the concept “furniture” is an abstraction one step further removed
from perceptual reality than any of its constituent concepts. “Table” is an
abstraction, since it designates any table, but its meaning can be conveyed
simply by pointing to one or two perceptual objects. There is no such
perceptual object as “furniture”; there are only tables, chairs, beds, etc. The
meaning of “furniture” cannot be grasped unless one has first grasped the
meaning of its constituent concepts; these are its link to reality. (On the
lower levels of an unlimited conceptual chain, this is an illustration of the
hierarchical structure of concepts.)