No, although "flash of genius" used to be the standard. Nowadays, an invention that is the product of patient experimentation, or an invention that was discovered entirely by accident, is just as patentable as one that arises from pure mental effort. See, e.g., Graham v. John Deere Co., 383 U.S. 1, 15 (1966); Life Technologies Inc. v. Clonetech Labs., Inc., 224 F.3d 1320, 1325 (Fed. Cir. 2000) ("the path that leads an inventor to the invention is...irrelevant to patentability"). The standard substantive requirements for a patent are utility, novelty, non-obviousness, written description, enablement, and best mode. Note that these topics have been covered extensively in other posts.