unseen power. 198. This account of the considerations which have regulated the punishment of crimes explains the severity with which 'criminal negligence' is in some cases punished, and that severity is justified by the account given of the true principle of criminal law, the principle, viz., that crime should be punished according to the importance of the right which it violates, and to the degree of terror which in a well-organised society needs to be associated with the crime in order to the protection of the right. It cannot be held that the carelessness of an engine-driver who overlooks a signal and causes a fatal accident, implies more moral depravity than is implied in such negligence as all of us are constantly guilty of. Considered with reference to the state of mind of the agent, it is on a level with multitudes of actions and omissions which are not punished at all. Yet the engine-driver would be found guilty of manslaughter and sentenced to penal servitude. The justification is not to be found in distinctions between different kinds of negligence on the part of different agents, but in the effect of the negligence in different cases upon the rights of others. In the case supposed, the most important of all rights, the right to life, on the part of railway passengers depends for its maintenance on the vigilance of the drivers. Any preventible failure in such vigilance requires to have sufficient terror associated with it in the mind of other engine-drivers to prevent the recurrence of a like failure in vigilance. Such punishment is just, however generally virtuous the victim of it is, because it is necessary to the protection of rights of which the protection is necessary to social well-being; and the victim of it, in proportion to his sense of justice, which means his habit of practically recognising true rights, will recognise it as just.