ל"ה - הלכות יין נסך ג:ד
The invention of the printing press has given us the ability to publish more and more of the writings of the tzaddikim, whose teachings provide us with the guidance we need to fulfill the Torah in practice and attain true spirituality. The printing press gives us the means of printing and distributing many, many books at a minimal price so that everyone in search of Godliness can find an antidote to his personal malaise.
The printing press bears comparison with the breastplate of the Kohen HaGadol, which was studded with twelve precious stones, each of which was engraved with the name of one of the Twelve Tribes of Yisrael. When a Jew needed advice or an answer to a question he would sanctify himself and pray, and then draw near to the Kohen HaGadol. The letters engraved on the stones of the breastplate would then shine to him one after the other, spelling out the answer he hoped for. (Yoma 73b) The Twelve Tribes constitute klal Yisrael as a whole. Each Jew requires a different approach to his problems and a unique solution. In our times, the ideas and answers each one needs are supplied by the many books produced by the printing press, the letters of which correspond to the letters engraved on the breastplate of the Kohen HaGadol. The letters shine and radiate when one approaches them properly for results.
*(this was not posted on Shabbos!)