greater in the association than it was in the individual elements. It
is simply adding two to one and getting three as a result. An
aggregation is unpatentable. As an illustration, a heavy marble statue
of Jupiter is found in the parlor and difficult to move. Ordinary
casters are put under its pedestal and it becomes easier to move.
Modern anti-friction two-wheeled casters are substituted for the
commoner casters, and the statue becomes still easier to move. Casters
were never before associated with a statue of Jupiter. Here is a new
association, but it is a mere aggregation. The statue of Jupiter has
been unmodified by the presence of the casters, and the casters
perform precisely the same under the statue of Jupiter that they did
under the bedstead. There is no combined result, and there is no
patentable combination.

But if an inventor takes a given mechanical element for the purpose of
its well recognized capacity, and then associates with it another
mechanical element for its recognized capacity, but so associates the
two elements that one has a modifying effect upon the capacity of the
other element, then the association will be capable of a result
greater than the sum of the results for the individual elements. This
excessive result is not due to the individual elements, but to the
combination of them. One has been added to one and a sum greater than
two has been secured. The modification of result may be due merely to
the bringing of the two elements together, so that they may mutually
act upon each other, or it may be due to the manner or means by which
they are joined. In a patentable combination the separate elements
mutually act upon each other to effect a modification of their
previous individual results, and secure a conjoint result greater than
the sum of the individual results. The elements of a combination need
not act simultaneously; they may act successively, or some may act