His mind runs along a certain train of ideas: The refusal of the soldiers to consent to his escape, the action of the executioner; the separation of the head and body; bleeding, convulsive motions, and death. Here is a connected chain of natural causes and voluntary actions; but the mind feels no difference betwixt them in passing from one link to another; nor is less certain of the future event than if it were connected with the present impressions of the memory and senses by a train of causes cemented together by what we are pleased to call a physical necessity. The same experienced union has the same effect on the mind, whether the united objects be motives, volitions and actions; or figure and motion. We may change the names of things; but their nature and their operation on the understanding never change.