The first Rule I shall propose to be observed is, that you never seem to dislike in another what the Jealous Man is himself guilty of, or to admire any thing in which he himself does not excel.  A Jealous Man is very quick in his Applications, he knows how to find a double Edge in an Invective, and to draw a Satyr on himself out of a Panegyrick on another.  He does not trouble himself to consider the Person, but to direct the Character; and is secretly pleased or confounded as he finds more or less of himself in it.  The Commendation of any thing in another, stirs up his Jealousy, as it shews you have a Value for others, besides himself; but the Commendation of that which he himself wants, inflames him more, as it shews that in some Respects you prefer others before him.  Jealousie is admirably described in this View by Horace in his Ode to Lydia [; [1]]

  Quum tu, Lydia, Telephi
   Cervicem roseam, et cerea Telephi
  Laudas brachia, vae meum
   Fervens difficili bile tumet jecur: 
  Tunc nec mens mihi, nec color
   Certa sede manet; humor et in genas
  Furtim labitur, arguens
   Quam lentis penitus macerer ignibus.

  When_ Telephus his youthful Charms,
  His rosie Neck and winding Arms,
  With endless Rapture you recite,
  And in the pleasing Name delight;
  My Heart, inflam’d by jealous Heats,
  With numberless Resentments beats;
  From my pale Cheek the Colour flies,
  And all the Man within me dies: 
  By Turns my hidden Grief appears
  In rising Sighs and falling Tears,
  That shew too well the warm Desires,
  The silent, slow, consuming Fires,
  Which on my inmost Vitals prey,
  And melt my very Soul away.

The Jealous Man is not indeed angry if you dislike another, but if you find those Faults which are to be found in his own Character, you discover not only your Dislike of another, but of himself.  In short, he is so desirous of ingrossing all your Love, that he is grieved at the want of any Charm, which he believes has Power to raise it; and if he finds by your Censures on others, that he is not so agreeable in your Opinion as he might be, he naturally concludes you could love him better if he had other Qualifications, and that by Consequence your Affection does not rise so high as he thinks it ought.  If therefore his Temper be grave or sullen, you must not be too much pleased with a Jest, or transported with any thing that is gay and diverting.  If his Beauty be none of the best, you must be a professed Admirer of Prudence, or any other Quality he is Master of, or at least vain enough to think he is.