The inside eye is a metaphor for one's imagination. So, when the poet is in a blank or contemplative mood, he is enjoying his isolation, and at that point, the sight of the daffodils flashes in his imagination (which is referred to as the happiness or blessing of solitude), and his heart fills with delight and begins dancing with the daffodils. This is why those who have never been alone can never understand what true bliss is like; they have no idea how great this pleasure is until they have experienced it themselves. For some people, being alone means being lonely, but this isn't always the case. Sometimes, it means having freedom. It's possible to be alone yet not feel alone because you are with yourself. You can think about your own thoughts and come up with your own ideas. This is why some people love being alone even though they might have some friends around them. They know that they will still be able to think freely because no one else is interfering with their mind. Being alone can also mean being isolated from others. If you are living by yourself in a home where no other people are present, then you are alone. Even if you go out during the day, come back home at night, and nobody knows where you've been or what you've done, you are still alone. This is why some people dislike being alone because they feel lost without anyone else around them. Finally, being alone can mean having privacy.