Philosophy is merely the widest science of all.

Its reasoning method is the same as that of any particular science and of all particular sciences.

And by that same method of reasoning, the inductive method, philosophy fuses all particular sciences into one great science.

As Spencer says, the data of any particular science are partially unified knowledge.

Philosophy unifies the knowledge that is contributed by all the sciences.
Philosophy is the science of science, the master science, if you please.
How do you like my definition ?" "Very creditable, very creditable," Dr.Hammerfield muttered lamely.
But Ernest was merciless.
"Remember," he warned, "my definition is fatal to metaphysics.