What is path and fruition?

Path and fruition for the 4 stages of holy disciple are frequently mentioned. I understand that the fruition is the removal of the fetters and realization of the knowledge of that respective attainment (stream entry, once returner, non returner, arhatship ). The holy disciple knows that he is a stream entrant upon attainment of stream entry fruition.......he knows he is an arhat upon attainment of arhatship. But what is the attainment of path? How would one describe rightly the attainment of the path? What is the difference in an ordinary person, a faithful disciple who has not attained any path and the holy one who has attained any of the respective path? I would really appreciate actual words of the Buddha for this answer.