Solidarity is a principle of Catholic Social Teaching and a Christian virtue articulated by Pope John Paul II which amplifies the concept of the common good and holds that for Christians it is essential to act in favor of the well being of all, particularly those who are most poor and marginalized from political influence. In Solicitudo Rei Socialis, a major document of Catholic Social Teaching, Pope John Paul II identifies the concept of solidarity with the poor and marginalized as a constitutive element of the Gospel and essential for lasting peace. Some quotes: