You don't indicate the book you are citing, but we can examine Rousseau's ideas about man being born free and those implications. Of the Enlightenment philosophers, there were three major theories of man's nature.
Jean-Jacques Rousseau believed that man is born inherently moral, and society is a corrupting influence. The only way for man to secure his freedom is to abide by a social contract, in which everyone's chief concern is civility, under a direct democracy.
Thomas Hobbes wrote that men were born in a state of savagery and could only find freedom through the structure government provides, including the structure of an absolute monarchy where one man could make decisions about the lives of all under his reign.
John Locke believed that man was born neither moral or savage but neutral, and the model of society would determine what a man would become. Locke believed in representative government, determined by the will of the people but then entrusted to those elected to govern.
In believing that man is born inherently noble, Rousseau indicates that man's first instinct is to act morally. Given this belief, man has the ability to better himself and society.
In his "Second Discourse," Rousseau outlines the ways in which man can deliberately improve society by observing the behaviors of himself and others and choosing to reject baser behaviors. According to Rousseau, perfectibility is the ability to become ever more civilized as society rejects uncivilized behavior.