The knowledge of these characters is founded on the observation of an uniformity in the actions, that flow from them; and this uniformity forms the very essence of necessity.
I can imagine only one way of eluding this argument, which is by denying that uniformity of human actions, on which it is founded.

As long as actions have a constant union and connexion with the situation and temper of the agent, however we may in words refuse to acknowledge the necessity, we really allow the thing.

Now some may, perhaps, find a pretext to deny this regular union and connexion.

For what is more capricious than human actions?
What more inconstant than the desires of man?
And what creature departs more widely, not only from right reason, but from his own character and disposition?
An hour, a moment is sufficient to make him change from one extreme to another, and overturn what cost the greatest pain and labour to establish.

Necessity is regular and certain.