to these later periods it shows great modifications, but this alteration is itself a proof of life. Philosophy, like religion, in so far as it has a real vitality, must change and adapt itself to altered conditions and new requirements: it can remain pure and true to its past only in so far as its life is artificial and unreal, lived in an academic atmosphere far removed from the life of the community at large. In such an unnatural atmosphere no doubt, it is possible for a religion or a philosophy to live perfectly pure and uncorrupt, but it is certainly not an ideal life: in real life there are bound to be introduced many unworthy elements and some which can only be described as actually corrupt. So it is inevitable that as a religion or a philosophy lives and really fulfils its proper functions it has to pass through many changes. Of course the same holds good for all other forms of culture: it may be true that a country is happy if it has no history, but it is the placid happiness of vegetable life, not the enjoyment of the higher functions of rational being.
In considering the transmission of Greek philosophy to the Arabs we see that philosophy still as a living force, adapting itself to changed conditions but without a break in the continuity of its life. It was not, as now, an academic study sought only by a group of specialists, but a living influence which guided men in their ideas about the universe in which they lived and dominated all theology, law, and social ideas. For many centuries it pervaded the
