METHODS OF STUDY 25 



as appurtenances of their rural estates, and such houses were 

 called " mural mansions," and were liable for the repair of the 

 city wall In other cities there were houses belonging to 

 the landowners of the county as appurtenances of their rural 

 estates : were such houses mural mansions or no ? The 

 position that I have taken in a former essay is that such 

 houses were mural mansions, on the principle that an explana- 

 tion of any phenomenon given in one passage should, in the 

 absence of any evidence to the contrary, be taken to be a 

 general explanation applicable to all similar phenomena. On 

 the other hand, it is contended that general rules were taken 

 as known, and that only the exceptions to these rules were 

 recorded. If the existence of houses liable for the repair of 

 the walls was an institution peculiar to Oxford, some other 

 explanation must be suggested for the existence in other 

 cities of houses appurtenant to rural estates ; but Domesday 

 Book hints at no other explanation. 



The Domesday student will not, therefore, be surprised 

 to find that many points still remain in doubt. In such cases 

 the evidence and arguments will be laid before him, and he 

 must form his own conclusions. 



A word of warning must be added : The student who finds 

 a custom or a distinction existing both in the ninth and the 

 thirteenth centuries, will naturally conclude that that custom 

 or distinction persisted during the interval between those 

 periods ; but he must be very careful not to import into 

 Domesday any custom or distinction of which the evidence 

 is found only in the ninth or the thirteenth century. Such 

 evidence may be properly adduced in corroboration of a 

 custom or distinction of which the Domesday evidence is 

 slight; but to import a thirteenth-century custom into the 

 eleventh century may involve almost as great an anachronism 

 as a picture of Hengist and Horsa arriving in torpedo-boats 

 and armed with Maxims. 



