Bards who believed more in the propagation of their learning by word of mouth than by writing still had a system of writing by runes, called Coelbren Y Beirdd. This alphabet's name derived from the words coel (to remember or to credit) and pren (wood), thus coelbren meant the alphabet used in cutting on wood that which was to be remembered or credited. This cutting was done on square or triangular rods of wood, usually oak. these rods were arranged in a set order within a frame, so that they could be turned as writing on each face of the rod was read. The whole arrangement was called the Peithynen. The letters of the alphabet or Coelbren Y Beirdd consisted entriely of straight lines, so as to facilitate their cutting upon wood. This was before the use of parchement and paper became common.