It was added to by many generations, and contained various information: diary-type entries on current events, memoirs, letters, political speeches, copies of legal documents, gossips, jokes and anecdotes, financial documents, economic information (price of grain, etc.), philosophical musings, poems, genealogical trees, advice (agricultural, medical, moral) for the descendants and others. The wealth of information in silva is staggering; they contain anything that their authors wished to record for future generations. Some silvae rerum were of truly enormous proportions, with thousands of pages (Gloger cites one of 1764 pages) although most common size is from 500 to 800 pages.
Source: Silva rerum – Wikipedia