As quoted (p. 112) in Fearful Majesty: The Life and Reign of Ivan the Terrible:
"If we consider the amount of time and resources spent upon this grim and exhausting struggle [against the Tartars], we shall have no need to ask ourselves what the Russian people were doing when the West was progressing rapidly in industry, in social life, in the arts and sciences, and in trade ... Fate set the Russian nation at the Eastern gate of Europe and for centuries it spent its forces in withstanding the pressure of Asiatic hordes while Western Europe turned to the New World beyond the seas ... Outpost service, however, is everywhere thankless, and soon forgotten, especially when it has been efficiently carried out. The more alert the guard, the sounder the slumbers of the guarded, and the less disposed the sleepers to value the sacrifices which have been made for their repose."
Russian historian V. O. Klyuchevsky, 1841-1911