The cat in gloves catches no mice.
Franklin uses the image of a cat wearing gloves to show how excessive delicacy can interfere with practical effectiveness. A cat depends on direct use of its paws to catch mice; gloves may appear protective or refined, but they prevent it from doing the task properly. The metaphor applies to people who become so cautious, formal or concerned with avoiding discomfort that they reduce their ability to achieve useful results.
The saying does not argue against care, courtesy or preparation. Its broader point is that these qualities become counterproductive when they obstruct necessary action. Some tasks require direct involvement, decisiveness and a willingness to accept inconvenience or minor risk. Franklin therefore contrasts appearance or excessive restraint with practical competence, suggesting that effective action depends on using the means appropriate to the task.