Analogy of a Journey
To understand better the idea of taking refuge, one might take the example of a traveller who wants to visit a distant city where he has never been to before. He will surely need a guide to lead him towards his destination. He will need a path to follow. He may also wish to have travelling companions on the journey. A Buddhist working towards attaining happiness and Enlightenment is like the traveller trying to reach that distant city. The Buddha is his "guide", the Dharma his "path" and the Sangha are his "travelling companions".
A Buddhist take refuge in the Buddha as his guide because he believes that the Buddha, having attained Enlightenment Himself, is able to guide him towards that goal. The Dharma that he takes as his refuge is like a path that has been well laid out. Such a path may include signposts to show directions, bridges for crossing rivers and steps for climbing mountains. Similarly, the Dharma includes the rules of Good Conduct to help him avoid unwholesome actions and the techniques of Mental Development to help him overcome distractions. It also teaches him how to overcome ignorance and gain Enlightenment.
Taking refuge in the Sangha is like having good travelling companions who keep a traveller company, care for him when he is sick and encourage him along when he is tired. The members of the Sangha, like ideal travelling companions, help the lay follower to purify his unwholesome ideas and correct his behaviour through sound advice and instruction, and encourage him to continue his journey to Enlightenment.