Now it is the nature of custom not only to operate with its full force, when objects are presented, that are exactly the same with those to which we have been accustomed; but also to operate in an inferior degree, when we discover such as are similar; and though the habit loses somewhat of its force by every difference, yet it is seldom entirely destroyed, where any considerable circumstances remain the same.

A man, who has contracted a custom of eating fruit by the use of pears or peaches, will satisfy himself with melons, where he cannot find his favourite fruit; as one, who has become a drunkard by the use of red wines, will be carried almost with the same violence to white, if presented to him.

From this principle I have accounted for that species of probability, derived from analogy, where we transfer our experience in past instances to objects which are resembling, but are not exactly the same with those concerning which we have had experience.

In proportion as the resemblance decays, the probability diminishes; but still has some force as long as there remain any traces of the resemblance.
This observation we may carry farther; and may remark, that though custom be the foundation of all our judgments, yet sometimes it has an effect on the imagination in opposition to the judgment, and produces a contrariety in our sentiments concerning the same object.

I explain myself.