Both brothers distinguish divination as a separate subject from the natural or even the applied sciences. Quintus says that medical men, pilots, and farmers foresee many things, yet their arts are not divination. “Not even Pherecydes, that famous Pythagorean master, who predicted an earthquake when he saw that the water had disappeared from a well which usually was well filled, should be regarded as a diviner rather than a physicist.”[1264] Tully carries the distinction a step further and asserts that the sick seek a doctor, not a soothsayer; that diviners cannot instruct us in astronomy; that no one consults them concerning philosophic problems or ethical questions; that they can give us no light on the problems of the natural universe; and that they are of no service in logic, dialectic, or political science.[1265] An admirable declaration of independence of natural science and medicine and other arts and constructive forms of thought from the methods of divination! But also one more easy to state in general terms of theory than to enforce in details of practice, as Pliny, Galen, and Ptolemy have already shown us. None the less it is indeed a noteworthy restriction of the field of divination when Cicero remarks to his brother, “For those things which can be perceived beforehand either by art or reason or experience or conjecture you regard as not the affair of diviners but of scientists.”[1266] But the question remains whether too large powers of prediction may not be claimed by “science.” [Sidenote: Unreasonable in method.] Cicero proceeds to attack the methods and assumptions of divination as neither reasonable nor scientific. Why, he asks, did Calchas deduce from the devoured sparrows that the Trojan war would last ten years rather than ten weeks or ten months?[1267] He points out that the art is conducted in different places according to quite different rules of procedure, even to the extent that a favorable omen in one locality is a sinister warning elsewhere.[1268] He refuses to believe in any extraordinary bonds of sympathy between things which, in so far as our daily experience and our knowledge of the workings of nature can inform us, have no causal connection. What intimate connection, he asks, what bond of natural causality can there be between the liver or heart or lung of a fat bull and the divine eternal cause of all which rules the universe?[1269] “That anything certain is signified by uncertain things, is not this the last thing a scientist should admit?”[1270] He refuses to accept dreams as fit channels either of natural divination or divine revelation.[1271] The Sibylline Books, like most oracles, are vague and the evident product of labored ingenuity.[1272] [Sidenote: Requires violation of natural law.]