It was promulgated eight months into the pontificate and addresses truth, unity and peace in the spirit of charity.

The document makes several references to the planned Second Vatican Ecumenical Council later held during 1962–1965.

It was neither a trend-setting social document or doctrinal exposition, but instead a fatherly message which was seen as addressing its issues with warmth and pastoral concern.

[2] The encyclical advocated for greater unity between churches, nations, classes of people and within families.

[3] The last part of the encyclical was a call to action in a number of crucial areas, including social justice and the combating of false ideas.