A nation may be defined as any considerable group of people who believe they are one; and their nationalism as the state of mind which sustains this belief. Broadly speaking, the sentiment of nationality is much the same in quality at all times and in all places. Its minimum content is love, or at least awareness, of one's country, and pride in its past achievements, real or fictitious; and it springs from attachment to the known and familiar, stimulated by the perception of difference–difference of habits and customs, often too of speech, from those of neighbouring peoples. The historical evidence for the existence of this positive sentiment in early times is largely inferential, a mere deduction from the struggles and mutual hatreds of tribes perpetually at war. But by the tenth or eleventh century there is evidence that medieval man was faintly stirred by the same sort of national impulses as we are, though he felt them in very different circumstances, in a different degree and, often, in relation to other objects. By the thirteenth century the fully developed medieval state had reached a momentary equilibrium, and if it was still “feudal”, it was also, in its way, a national state. Then as now, nationality was in general, though not necessarily, coterminous with a vernacular.