John Lennon gave us that wonderful phrase "All You Need IS Love", besides other quotes that are not as well known.
I personally like this one:
"We've got this gift of love, but love is like a precious plant. You can't just accept it and leave it in the cupboard or just think it's going to get on by itself. You've got to keep watering it. You've got to really look after it and nurture it."
Plain simple words we all can agree on.