Chapter 2 begins today, detailing “The Practice Of Ecumenism.”
The attainment of union is the concern of the whole Church, faithful and shepherds alike. This concern extends to everyone, according to his talent, whether it be exercised in his daily Christian life or in his theological and historical research. This concern itself reveals already to some extent the bond of (communion) between all Christians and it helps toward that full and perfect unity which God in His kindness wills.
Simple enough: ecumenism is not just for theologians; not just for ordinary people.