I'm Reading Orthodoxy

Buddhism is centripetal, but Christianity is centrifugal: it breaks out. For the circle is perfect and infinite in its nature: but it is fixed for ever in its size; it can never be larger or smaller. But the cross, though it has at its heart a collision and contradiction, can extend its four arms forever without altering its shape. Because it has paradox in its centre it can grow without changing. The circle returns upon itself and is bound. The cross opens its four arms to the winds; it is a signpost for free travelers.

(Chap. 2: The Maniac, Orthodoxy)