Aristotle, Politics

[1330b] [1] and among the remaining considerations, a sloping site is favorable both for political and for military purposes. For military purposes therefore the site should be easy of exit for the citizens themselves, and difficult for the adversary to approach and to blockade, and it must possess if possible a plentiful natural supply of pools and springs, but failing this, a mode has been invented of supplying water by means of constructing an abundance of large reservoirs for rain-water, so that a supply may never fail the citizens when they are debarred from their territory by war. And since we have to consider the health of the inhabitants, and this depends upon the place being well situated both on healthy ground and with a healthy aspect, and secondly upon using wholesome water-supplies, the following matter also must be attended to as of primary importance. Those things which we use for the body in the largest quantity, and most frequently, contribute most to health; and the influence of the water-supply and of the air is of this nature. Hence in wise cities if all the sources of water are not equally pure and there is not an abundance of suitable springs, the water-supplies for drinking must be kept separate from those for other requirements. As to fortified positions, what is expedient is not the same for all forms of constitution alike; for example, a citadel-hill is suitable for oligarchy and monarchy, [20] and a level site for democracy; neither is favorable to an aristocracy, but rather several strong positions. The arrangement of the private dwellings is thought to be more agreeable and more convenient for general purposes if they are laid out in straight streets, after the modern fashion, that is, the one introduced by Hippodamus¹; but it is more suitable for security in war if it is on the contrary plan, as cities used to be in ancient times; for that arrangement is difficult for foreign troops² to enter and to find their way about in when attacking. Hence it is well to combine the advantages of both plans （for this is possible if the houses are laid out in the way which among the farmers some people call ‘on the slant’³ in the case of vines）, and not to lay out the whole city in straight streets, but only certain parts and districts, for in this way it will combine security with beauty.

As regards walls, those who aver that cities which pretend to valor should not have them hold too old-fashioned a view—and that though they see that the cities that indulge in that form of vanity are refuted by experience. It is true that against an evenly matched foe and one little superior in numbers it is not honorable to try to secure oneself by the strength of one's fortifications; but as it does and may happen that the superior numbers of the attackers may be too much for the human valor of a small force, if the city is to survive and not to suffer disaster or insult, the securest fortification of walls must be deemed to be the most warlike,