He who has a suspicious mind is ever the prey of worry.  Such an one is to be pitied for he is tossed hither and yon, to and fro, at the whim of every breath of suspicion he breathes.  He has no real peace of mind, no content, no unalloyed joy, for even in his hours of pleasure, of recreation, of expected jollity he is worrying lest someone is trying to get ahead of him, his vis-a-vis is “jollying” him, his partner at golf is trying to steal a march on him, he is not being properly served at the picnic, etc.

These suspicious-minded people are sure that every man is a scoundrel at heart—­more or less—­and needs to be watched; no man or woman is to be trusted; every grocer will sand his sugar, chicory his coffee, sell butterine for butter, and cold-storage eggs for fresh if he gets a chance.  To accept the word of a stranger is absurd, as it is also to believe in the disinterestedness of a politician, reformer, office-holder, a corporation, or a rich man.  But to believe evil, to expect to be swindled, or prepare to be deceived is the height of perspicacity and wisdom.  How wonderfully Shakspere in Othello portrays the wretchedness of the suspicious man.  One reason why Iago so hated the Moor was that he suspected him: 

               the thoughts whereof
  Doth like a poisonous mineral gnaw my inwards,
  And nothing can or shall content my soul
  Till I am even’d with him.

How graphic the simile, “gnaw my inwards;” it is the perpetual symbol of worry; the poisonous mineral ever biting away the lining of the stomach; just as mice and rats gnaw at the backs of the most precious books and destroy them; aye, as they gnaw during the night-time and drive sleep away from the weary, so does suspicion gnaw with its sharp worrying teeth to the destruction of peace, happiness and joy.

Then, when Iago has poisoned Othello’s mind with suspicions about his wife, how the Moor is worried, gnawed by them: 

    By heaven, he echoes me,
  As if there were some monster in his thought
  Too hideous to be shown—­(To Iago) Thou dost mean something. 
  I heard thee say even now, thou lik’dst not that,
  When Cassio left my wife; what didst not like? 
  And when I told thee he was of my counsel
  In my whole course of wooing, thou criedst ‘Indeed!’
  And didst contract and purse thy brow together,
  As if thou then hadst shut up in thy brain
  Some horrible conceit.  If thou dost love me,
  Show me thy thought.

And then we know, how, with crafty, devilish cunning, Iago plays upon these suspicions, fans their spark into flames.  He pretends to be doing it purely on Othello’s account and accuses himself that: 

it is my nature’s plague
To spy into abuses, and yet my jealousy
Shapes faults that are not: 

and then cries out: 

           O beware, my lord, of jealousy! 

It is the green-eyed monster which doth mock
The meat it feeds on.  That cuckold lives in bliss
Who certain of his fate, loves not his wronger;
But, O, what damned minutes tells he o’er
Who dotes, yet doubts, suspects, yet strongly loves!