When CGC was getting started there were dealers and prominent collectors with high-dollar GA books, including Church and other pedigree copies, that had spine splits sealed with a bit of glue or had small amounts of ct. If CGC's policy had been to put those books in purple labels, the books would not have been submitted and CGC would have had trouble gaining support from those collectors and dealers.   Given the skepticism that existed at the time as to whether grading and encapsulating comi