4. We gladly avail Ourselves of the 25th anniversary of the Encyclical Letter Rerum Ecclesiae to express Our appreciation of the work which has been accomplished and the great consolation it has given Us, and further to exhort all to go forward with still greater zeal: all Our venerable brethren in the Episcopacy, We mean, all missionaries, priests and individual faithful, both in missionary lands and throughout the whole world, who by their prayers, by training and helping future missionaries, or by obtaining material aid promote this most important work.