Under him we trace a growing relaxation of the checks by which the great officers of the state were intended to have been held under restraint.

Satraps came to be practically uncontrolled in their provinces, and the dangerous custom arose of allowing sons to succeed, almost as a matter of course, to the governments of their fathers.
Powers unduly large were lodged in the hands of a single officer, and actions, that should have brought down upon their perpetrators sharp and signal punishment, were timorously or negligently condoned by the supreme authority.

Cunning and treachery were made the weapons wherewith Persia contended with her enemies.

Manly habits were laid aside, and the nation learned to trust more and more to the swords of mercenaries.
Shortly before the death of Darius there seems to have been a doubt raised as to the succession.

Parysatis, who preferred her second son to her first-born, imagined that her influence was sufficient to induce her husband to nominate Cyrus, instead of Arsaces, to succeed him; and Cyrus is said to have himself expected to be preferred above his brother.