 Competent judges will find that the opinions which he then sets down as the more tenable are in the majority of cases the more correct".Until today only few very valuable books have been conserved and usually those books can be found only in private collections or universities.The medium price of any of those very rare books is between US$65,000 and 150,000 on the market (last licitation of "Opera omnia" was sold to a private collector at the price of US$95,000).