Thucydides (c. 51) affirms, that the infection could only be once taken; but Evagrius, who had family experience of the plague, observes, that some persons, who had escaped the first, sunk under the second attack; and this repetition is confirmed by Fabius Paullinus (p. 588.). I observe, that on this head physicians are divided; and the nature and operation of the disease may not always be similar.