What is douglass argument about escaped slaves recounting their methods of escape, and what reasons does he give to support his claim?

In the final chapter of his narrative, Douglass explains that he does not describe his escape with precision, because he does not want to give any advantage to slave owners. Giving them too many details of how did he escape would help slave owners to prevent the escape of their slaves to the North. Douglass hopes to generate in the slave owners a certain feeling of paranoia, and make it as difficult as possible for them to retain their slaves.