is the result of the combined effect of the tangential energy with which it is endowed, and the centripetal energy which operates from the sun.  In this simile the former energy represents character, and the latter the influence of motive.  It is almost more than a mere simile.  The tangential energy which properly speaking is the source of the planet’s motion, whilst on the other hand the motion is kept in check by gravitation, is, from a metaphysical point of view, the will manifesting itself in that body.

To grasp this fact is to see that we really never form anything more than a conjecture of what we shall do under circumstances which are still to happen; although we often take our conjecture for a resolve.  When, for instance, in pursuance of a proposal, a man with the greatest sincerity, and even eagerness, accepts an engagement to do this or that on the occurrence of a certain future event, it is by no means certain that he will fulfil the engagement; unless he is so constituted that the promise which he gives, in itself and as such, is always and everywhere a motive sufficient for him, by acting upon him, through considerations of honour, like some external compulsion.  But above and beyond this, what he will do on the occurrence of that event may be foretold from true and accurate knowledge of his character and the external circumstances under the influence of which he will fall; and it may with complete certainty be foretold from this alone.  Nay, it is a very easy prophecy if he has been already seen in a like position; for he will inevitably do the same thing a second time, provided that on the first occasion he had a true and complete knowledge of the facts of the case.  For, as I have often remarked, a final cause does not impel a man by being real, but by being known; causa finalis non movet secundum suum esse reale, sed secundum esse cognitum.[1] Whatever he failed to recognise or understand the first time could have no influence upon his will; just as an electric current stops when some isolating body hinders the action of the conductor.  This unalterable nature of character, and the consequent necessity of our actions, are made very clear to a man who has not, on any given occasion, behaved as he ought to have done, by showing a lack either of resolution or endurance or courage, or some other quality demanded at the moment.  Afterwards he recognises what it is that he ought to have done; and, sincerely repenting of his incorrect behaviour, he thinks to himself, If the opportunity were offered to me again, I should act differently.  It is offered once more; the same occasion recurs; and to his great astonishment he does precisely the same thing over again.[2]

[Footnote 1:  Suarez, Disp.  Metaph., xxiii.; Sec.Sec.7 and 8.]

[Footnote 2:  Cf. World as Will, ii., pp. 251 ff. sqq. (third edition).]