[Footnote 91: 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.]