835 "Let us be very careful not to conceive of the universal Church as the simple sum, or . . . the more or less anomalous federation of essentially different particular churches. In the mind of the Lord the Church is universal by vocation and mission, but when she pu[t] down her roots in a variety of cultural, social, and human terrains, she takes on different external expressions and appearances in each part of the world."318 The rich variety of ecclesiastical disciplines, liturgical rites, and theological and spiritual heritages proper to the local churches “unified in a common effort, shows all the more resplendently the catholicity of the undivided Church.” 319