'Serpents,' in the Word, signify sensory principles which are the extremes of a person's life. This is because all animals signify affections of people, which is why the affections of angels and spirits in the spiritual world also appear at a distance as animals. Mere sensory affections appear as 'serpents.' This because serpents crawl on the ground, and lick the dust, and sensory things are the lowest part of the understanding and will, being most closely connected with the world fed by its objects and delights, which affect only the physical senses of the body. Harmful serpents symbolize sensory things dependent on the evil affections that form the interior motivations of the mind in people who, owing to the falsities accompanying evil, are irrational. Harmless serpents symbolize sensory matters dependent on the good affections that form the interior motivations of the mind in people who, owing to the truths accompanying goodness, are wise.

(Referencat: Matthew 10, 10:16, Matthew 16)