Benjamin Graham says

Benjamin Graham was a professional investor, wrote Security Analysis and taught Warren Buffett. His book is heavy going for the uninterested, so how to sum up Graham's advice for the nonreader? Luckily Graham did it himself. I am looking at a typescript of a talk he gave in 1963 (literally a typescript, no powerpoint in those days)

In my nearly fifty years of experience* on Wall St I've found that I know less and less about what the stock market is going to do but I know more and more about what investors ought to do..... the investor is required by the very insecurity ruling in the world of today to maintain at all times some division of his funds between bonds and stocks (cash and various types of interest-bearing deposits may be viewed as bond equivalents). My suggestions is that the minimum position of this portfolio is 25% and the maximum should be 75%.

For comparison the suggested range for the vanilla investor is from 20% equities up to 67% equities (the 'bouncy' bit of the portfolio); giving a range on the 'boring' side (gilts/cash etc) from 80% to 33%. The Graham prescription is riskier (but potentially more rewarding) but even on the 'bond' side he urges caution:

nobody can assume he can get exactly the same degree of safety and dependability in [an] investment yielding 5% as in one yielding 4%.

Wise words as the junk bond era was still to come.

*His career spanned some turbulent times:

I would like to point out that the last time I made any stock market predictions was in the year 1914 when my firm judged me qualified to write their daily market letter

The lecture notes originally cost 50c but you can get them, free, here: http://www.jasonzweig.com/documents/BG_speech_SF1963.pdf