Whenever we penetrate to the heart of things, we always find a mystery. Life and all that goes with it is unfathomable…Knowing of life is recognition of the mysterious.
From a theological point of view, the word "mystery" doesn't just mean bewildering or incomprehensible. It means overwhelmingly sacred.
UPDATE: I was reading the Wikipedia article on Schweitzer that I linked you to above and found this:
Respect for life, resulting from contemplation on one's own conscious will to live, leads the individual to live in the service of other people and of every living creature. Schweitzer was much respected for putting his theory into practice in his own life. He was, for instance, a well-known cat lover, who, although left-handed, would write with his right hand rather than disturb the cat who would sleep on his left arm.
How wonderful! Anyone who has lived with cats completely understands this!