The muses love the morning.
Franklin invokes the Muses, the classical figures associated with poetry, learning and the arts, to suggest that creative and intellectual work is especially well suited to the morning. The phrase treats inspiration figuratively: a quiet, fresh start to the day may provide conditions in which writing, study or other concentrated work can proceed with fewer distractions.
The saying does not establish a universal rule that creativity is strongest early in the day, since people differ in when they work most effectively. Its broader point is that inspiration can depend partly on habit and circumstances rather than appearing entirely by chance. By reserving a favourable period for demanding or imaginative work, a person may make sustained creative effort easier. The proverb therefore links productivity with choosing conditions that support attention and thought.