A man living absolutely alone in a desert or forest is free from other people; but he is not absolutely free. His freedom is limited in several ways. Firstly, by the things around him, such as wild animals or cliffs too steep to climb. Secondly, by his own needs: he must have sleep, water, food and shelter from extreme heat or cold. Lastly, by his own nature as a man: disease may attack him, and death will certainly come to him sooner or later.
When men live together, on the other hand, protection against wild animals is easier and they can work together to get food and build shelters; but each man has to give up some of his freedom so that he can live happily with the others.
When men become organized into very large groups, and civilization develops, it is possible to get freedom from hunger, thirst, cold, heat and many diseases, so that each person can live a happier life than he could if he were living alone; but such a society can not work successfully unless the freedom of each human being is to some extent limited so that he is kept from hurting others. I am not free to kill others, nor to steal someone else's property, nor to behave in a way that offends against the moral sense of the society in which I live. I have to limit my own freedom myself so that others will not limit it too much: I agree to respect the rights of others, and in return they agree to respect mine.
The advantages of such an agreement are great : one man can become a doctor, knowing that others will grow food, make clothes and build a house for him, in return for the work he does to keep them healthy. If each man had to grow his own food, make his own clothes, build his own house and learn to be his own doctor, he would find it impossible to do any one of these jobs really well. By working together, we make it possible for society to provide us all with food, clothes, shelter and medical care, while leaving each of us with as much freedom as it can.