Some very basic background from a famous patent case (Diamond v. Chakrabarty):
"Anything under the sun that is made by man [is patentable] . . . . [T]he laws of nature, physical phenomena, and abstract ideas have been held not patentable . . . a new mineral discovered in the earth or a new plant found in the wild is not patentable subject matter. Likewise, Einstein could not patent his celebrated law that E=mc2; nor could Newton have patented the law of gravity. Such discoveries are manifestations of nature, free to all men and reserved exclusively to none."
"Anything under the sun that is made by man [is patentable] . . . . [T]he laws of nature, physical phenomena, and abstract ideas have been held not patentable . . . a new mineral discovered in the earth or a new plant found in the wild is not patentable subject matter. Likewise, Einstein could not patent his celebrated law that E=mc2; nor could Newton have patented the law of gravity. Such discoveries are manifestations of nature, free to all men and reserved exclusively to none."