A book I would highly recommend is 'The Extended Circle: A Dictionary of Humane Thought' by Jon Wynne-Tyson.

Over 400 pages of some of the most beautiful, compassionate thinking you'll ever come across.
This is very much a book for our time and I cannot believe that anyone could read this book and fail to emerge a better person.
It certainly had a huge impact on me.

'Until he extends the circle of his compassion to all living things, man will not himself find peace' - Albert Schweitzer