be warned to withdraw, before the organ be quite put out of order, and so be unfitted for its proper function for the future.  The consideration of those objects that produce it may well persuade us, that this is the end or use of pain.  For, though great light be insufferable to our eyes, yet the highest degree of darkness does not at all disease them:  because that, causing no disorderly motion in it, leaves that curious organ unarmed in its natural state.  But yet excess of cold as well as heat pains us:  because it is equally destructive to that temper which is necessary to the preservation of life, and the exercise of the several functions of the body, and which consists in a moderate degree of warmth; or, if you please, a motion of the insensible parts of our bodies, confined within certain bounds.

5.  Another end.

Beyond all this, we may find another reason why God hath scattered up and down several degrees of pleasure and pain, in all the things that environ and affect us; and blended them together in almost all that our thoughts and senses have to do with;—­that we, finding imperfection, dissatisfaction, and want of complete happiness, in all the enjoyments which the creatures can afford us, might be led to seek it in the enjoyment of Him with whom there is fullness of joy, and at whose right hand are pleasures for evermore.

6.  Goodness of God in annexing pleasure and pain to our other ideas.

Though what I have here said may not, perhaps, make the ideas of pleasure and pain clearer to us than our own experience does, which is the only way that we are capable of having them; yet the consideration of the reason why they are annexed to so many other ideas, serving to give us due sentiments of the wisdom and goodness of the Sovereign Disposer of all things, may not be unsuitable to the main end of these inquiries:  the knowledge and veneration of him being the chief end of all our thoughts, and the proper business of all understandings.

7.  Ideas of Existence and Unity.

Existence and unity are two other ideas that are suggested to the understanding by every object without, and every idea within.  When ideas are in our minds, we consider them as being actually there, as well as we consider things to be actually without us;—­which is, that they exist, or have existence.  And whatever we can consider as one thing, whether a real being or idea, suggests to the understanding the idea of unity.

8.  Idea of Power.

Power also is another of those simple ideas which we receive from sensation and reflection.  For, observing in ourselves that we do and can think, and that we can at pleasure move several parts of our bodies which were at rest; the effects, also, that natural bodies are able to produce in one another, occurring every moment to our senses,—­we both these ways get the idea of power.

9.  Idea of Succession.