"It is your opportunity to study under someone who has done a specific kind of research, and learn from that person. " That is what is it supposed to be, but I

"It is your opportunity to study under someone who has done a specific kind of research, and learn from that person. " That is what is it supposed to be, but I must interject that for many, myself included, the advisor is effectively absent. In a lab without postdocs or other students what I personally ended up with is an apprenticeship in learning from myself. If you are seeing your advisor more than once or twice a year, and or if there are other people in your lab to discuss your work with then you are doing your PhD in easy mode.