If I'm not mistaken, that wise investor was Warren Buffett
But you should keep in mind that blindly buying something in the down market is no guarantee of success. On the contrary, it is in fact a recipe for disaster. What Warren Buffett meant is that valuable assets in such a market are heavily oversold and undervalued, so you can buy them really cheap, that's true indeed, but valuable asset is not equal any asset. Thus, you should first find such an asset and distinguish it from other assets, i.e. do what every wise investor does all the time