The Fool as The Dreamer
Modern decks place the Fool at the beginning of the journey and show the innocence of the spiritual seeker with no idea of how much of an adventure he's embarking on. The Fool is about to jump on a ledge, often motivated by love or eros, as shown in the rose held in his right hand (from the viewer's point of view), and for only companion a dog which represents the instincts.
It's quite a different picture on the original Marseilles decks, where the card is usually placed at the end of the deck (although since it's unnumbered the card could be anywhere, or according to Paul Marteau after a multiple of seven – The Chariot, Temperance, or the World). It shows the state of a seeker who by his strange outfit and half-nakedness represents an eclectic mixture of nature and remnants of culture.
Apparently, the bells on his outfit prevent him from "finding his divine memories and forces him to walk", but the way I picture it you can also hear him coming from miles away, so there's a certain predictability that comes with the outfit. He's always walking the same path.
A person can have significant dreams or mystical experiences, which can easily bring feelings of enlightenment, but without putting the time and effort to cultivate and understand these experiences in the light of reason and objectivity the seeker remains an eternal dreamer or wanderer.
The Fool Reversed as The Organizer
The flip side of the eternal dreamer is the person who follows others in their quest, whether through a church, guru, self-help program or organization, and lacking a certain individuality to reach true freedom. That person needs a bit more dreaming to detach from the herd.
The positive side of the Organizer, however, is the ability to keep up with daily demands and routines, a very useful skill while embarking on an inner adventure. In his memoirs, Jung would say of Nietzsche that he lost his mind because he only had the inner world of his thoughts, as opposed to Jung who had professional and family obligations to keep him on the ground.
In the midst of his great adventure, Walter Mitty still took the time to balance his checkbook and check on his mom and sister.
The ideal seeker is a mix of Dreamer and Organizer.