Hollis's citation in context:
If we look hard enough, we will find anxiety, or its management, at the roots of so much we do. It is disconcerting to realize this fact, but in recognition of the ubiquity of anxiety in our lives and in those around us we may feel greater compassion for ourselves and for each other. Philo of Alexandria is reported to have said, “Be kind. Everyone you meet is carrying a big problem.” If we can accept that about ourselves and each other, accept the normality of anxiety, seek the roots of identifiable fears in that anxiety, then simply do the best that we can and forgive the rest, we may at last become less anxious.Quote Investigator contests the attribution to Philo (or, as often, to Plato).