In January 1949, Ben Graham spoke before the New York State Bankers Association to encourage bankers to advise customers on sound investment policy. What surprised people then was his push for simplicity.
You can make investing as simple or complicated as you want. Simple strategies tend to require less knowledge, fewer decisions, and generally easier to manage. Complicated strategies tend to bring added costs (higher fees and behavioral costs) and can introduce unknown, often uncompensated, risks.
Graham’s simple strategy: divide your portfolio between government bonds and a diversified basket of common stocks or “investment — fund shares — instead of a selected common stock list.” He purposely left out corporate bonds, preferred stocks, and the like, as unneeded risks for a defensive investor.