The connexion between the volitions of created will and effects, and the connexion between physical causes and effects, supposing each of course to be in its proper relations and circumstances, is a connexion of relative necessity; that is, relative to the divine will. Now the certainty of our knowledge or conviction that an event will take place, depending upon volition or upon a physical cause, is plainly different from the certain knowledge of a necessary truth, or the certain conviction that an event which infinite power wills, will take place. The will which established the connexion, may at any moment suspend or change the connexion. I believe that when I will to move my hand over this paper, it will move, supposing of course the continued healthiness of the limb; but it is possible for God so to alter the constitution of my being, that my will shall have no more connexion with my hands than it now has with the circulation of the blood. I believe also that if I throw this paper into the fire, it will burn; but it is possible for God so to alter the constitution of this paper or of fire, that the paper will not burn; and yet I have a certain belief that my hand will continue to obey volition, and that paper will burn in the fire. This certainly is not an _absolute certainty_, but a _conditional_ certainty: events will thus continue to take place on condition the divine will does not change the condition of things. This conditional certainty is likewise called a _physical_ certainty, because the events contemplated include besides the phenomena of consciousness, which are not so commonly noticed, the events or phenomena of the physical world, or nature. But we must next look at will itself in relation to its volitions: Here all is contingency and freedom,--here is no necessity. Is there any ground of certain knowledge respecting future volitions?