What did dr. hutchins mean when he said, "if we would change the face of the earth, we must first change our own hearts"?

With this quoatation from Dr. Hutchins "if we would change the face of the earth, we must first change our own hearts" , he wanted to express two great thruths:

First, to change the exterior of something means nothing if there is not a change in the core.

Second, that we humans have a decisive influence in the future of our planet, and if we want to improve its condition, we must first truly believe in those changes. We must have the good deeds and intentions to improve the life condition in the planet.

The phrase “"if we would change the face of the earth, we must first change our own hearts" is part of Dr. Hutchins interview on a radio as a response to President Roosevelt’s speech before the congress in 1941 to ask for support to enter World War II. According to Hutchins, American society was not prepared to go to war as it lacked some of the attributes that Roosevelt mentioned in his speech such as freedom of speech, freedom of religion and no discrimination against minority groups.  Therefore, why should America go to war based on these principles if it did not implement them here? So the phrase mentioned earlier explains that America must first try to embrace and acknowledge those principles before asking other countries to do it.

islam spread slowly through much of africa through trade and preaching.