but they must both meet and strike each other in the centre of the table, and, being perfectly elastic, the red ball must pass to the west pocket, and the white ball to the south pocket.  We may suppose that the players acted wholly without concert with each other, indeed, they may be ignorant of each other’ s design, or even of each other’s existence; still we know that the events must happen as herein described.  Now, the first half of the course of these two balls is from an impulse, or proceeds from a power, acting from design.  Each player has the design of driving his ball across the table in a diagonal line to accomplish its lodgment at the opposite corner of the table.  Neither designed that his ball should be deflected from that course and pass to another corner of the table.  The direction of this second part of the motion must be referred entirely to necessity, which directly interferes with the purpose of him who designed the rectilinear direction.  We are not, in this case, to go back to find design in the creation of the powers or laws of inertia and elasticity, after the order of which the deflection, at the instant of collision, necessarily takes place.  We know that these powers were inherent in the balls, and were not created to answer this special deflection.  We are required, by the hypothesis, to confine attention in point of time, from the instant preceding the impact of the balls, to the time of their arrival at the opposite corners of the table.  The cues aremoved by design.  The impacts are acts from design.  The first half of the motion of each ball is under the direction of design.  We mean by this the particular design of each player.  But, at the instant of the collision of the balls upon each other, direction from design ceases, and the balls no longer obey the particular designs of the players, the ends or purposes intended by them are not accomplished, but frustrated, by necessity, or by the necessary action of the powers of inertia and elasticity, which are inherent in matter, and are not made by any design of a Creator for this special action, or to serve this special purpose, but would have existed in the materials of which the balls were made, although the players had never been born.

I have thus stated, by a simple example in physical action, what is meant by design and what by necessity; and that the latter may exist without any dependence upon the former.  If I have given the statement with what may be thought, by some, unnecessary prolixity, I have only to say that I have found many minds to have a great difficulty in conceiving of necessity as acting altogether independent of design.