Political philosophy cannot be learnt from text-books. If it be true -
"That nature always does contrive That every boy and every gal That's born into the world alive Is either a little Liberal, Or else a little Conservative,"
then the most interesting problems of political philosophy must remain matters of controversy. It is perhaps for this reason that students are generally asked to approach the subject by way of the study of the writings of certain political philosophers that are generally regarded as classical. Or it may be because, as Aristotle said -
"It would probably be right to suppose that not only these but all other political discoveries have been made repeatedly, or rather an infinite number of times in the lapse of ages... It is our duty then while we avail ourselves adequately of the discoveries of the past, to endeavour to fill up the deficiencies that remain" (Politics, Bk. IV. chap. 10).