No sooner was the war with Venice over than Achmet found himself involved with a very different Christian power in the extreme northern frontier of the empire. The kingdom of Poland, to which was joined the grand duchy of Lithuania, had discharged during the Middle Ages the office of the sentinel of Western civilisation on its northern frontier. But the civilisation to which it had itself attained was very inferior to that of its southern and western neighbours. Extending as it did, so late as the beginning of the seventeenth century, from Livonia and Courland on the Baltic to Podolia and the lower waters of the Dniester on the confines of the Black Sea, it could not fail to be subject to the dangers of disunion and disorganisation. Its interests were so varied, its territories so impassable and heterogeneous, its people so untameable and independent, that it was almost a hopeless task for even a great statesman to inspire the country with a sense of national unity, and to lead it along the path of national progress. Yet forces which under happier circumstances might have led to contralization were not wanting. Poland occupied geographically the centre of Europe. Until the rise of Russia on the north and Prussia to the west it was free from serious danger of conquest. Its people were Sclavonic by race and Catholic by religion. With the exception of a few years at the end of the sixteenth century it was untroubled by religious or racial discord. Brave and chivalrous by nature the Poles were distinguished for their personal loyalty and their affection for their country. [Sidenote: =Turbulence of the Poles.=] But all these promising elements of union and strength weighed as nothing in the balance, when compared with the evils of their political and social institutions. The Poles were absolutely deficient in the capacity for being governed. They never appreciated the advantages of the reign of law. They never understood that individuals must submit to some restrictions if the community is to prosper. Discipline was a virtue wholly unrecognised by them. This lawless and turbulent spirit was fostered instead of being checked by their social institutions. [Sidenote: =Their social and constitutional institutions.=] There were but two classes in Poland, the aristocracy in whose hands lay the whole of the wealth and the whole of the political power, and the serfs who were little better than slaves, and had no rights of life or property against their masters. As in all countries where one class is dominant, justice and patriotism shrank and withered before the claims of privilege and selfishness. The determination to use the power which it has got solely for its own purposes, is not the monopoly of one class more than another. It has been the characteristic of the petty democracy of Florence, as of the trading aristocracy of Amsterdam, or the militant democracy of modern France. The landlord aristocracy of Poland pushed it to excess.