FYI: (Click On Article Title At Top Of Google Search)
Oh, the good old days!
When I started following the market in 1965 I could look back at what we might call the Ben Graham training period of 1935-1965. He noticed financial relationships and came to the conclusion that for patient investors the important ratios always went back to their old trends. He unsurprisingly preferred larger safety margins to smaller ones and, most importantly, more assets per dollar of stock price to fewer because he believed margins would tend to mean revert and make underperforming assets more valuable.
Regards,
Ted
https://www.google.com/#q=Grantham:+Don’t+Expect+P/E+Ratios+to+Collapse