INTRODUCTION. 1 9 



theories and fanciful speculations. But with all this we 

 hear of certain beliefs and practices which plainly fore- 

 shadowed those of the present day. Latin writers nearly 

 two thousand years ago recorded a relation between insects 

 and malaria, which has but lately been proved and ex- 

 plained. The treatment of lepers by the Hebrews resembles 

 that now in vogue : " He is unclean : he shall dwell alone ; 

 without the camp shall his habitation be " (Lev. XIII. 46). 

 There is, in fact, much in the laws of Moses that points to 

 some knowledge of the nature of infections. ' This is the 

 law, when a man dieth in a tent : all that come into the tent 

 and all that is in the tent shall be unclean for seven days. 

 And every open vessel which has no covering upon it shall 

 be unclean" (Numb. XIX. 14, 15). 



" Everything that may abide the fire, ye shall make it go 

 through the fire, and it shall be clean " (Numb. XXXI. 23). 



In Homer we read of Ulysses, that, having slain his 

 wife's troublesome suitors : 



" With fire and sulphur, cure of noxious fumes, 



He purged the walls and blood-polluted rooms" (Pope's Odyssey). 



The massive aqueducts of the Romans still remain to 

 testify that they understood the importance of a pure water- 

 supply. 



In Rome there were also sewers for the disposal of drain- 

 age; while the Cretans and Assyrians used sewerage sys- 

 tems hundreds and even thousands of years before. 



About the fourteenth century we find quarantine against 

 infectious diseases, plague in particular, practiced by certain 

 Italian cities ; and the word " quarantine " came into use 

 from the fact that the period of detention was about forty 

 days (Ital. quarantine*) * 



1 The Early History of Quarantine, J. M. Eager, Yellow Fever hist. 

 Bui., No. 12, U. S. Marine Hosp. Service. 



