In United States patent law, the doctrine of inherency holds that, under certain circumstances, prior art may be relied upon not only for what it expressly teaches, but also for what is inherent therein, i.e., what necessarily flows from the express teachings. For a patent claim to be valid, its subject-matter must be novel and non-obvious. The claim is anticipated if a single prior art reference, either expressly or inherently, discloses every feature of the claimed invention. The concept of inherency is predicated on the idea that a claim should not pass the test of anticipation merely because a feature of it is undisclosed or unrecognized in the prior art reference. A prior art source may thus still anticipate if an apparently missing element of the claim is inherent in that prior art source.