The following commentary comes from an independent investor or market observer as part of TheStreet's guest contributor program, which is separate from the company's news coverage.NEW YORK ( TheGoldAndOilGuy.com) -- Over the past five months we have seen volatility steadily decline as stocks and commodities rise in value. The volatility index is now trading at a level that has preceded many selloffs in the stock market over the years as investors become more and more comfortable and greedy with rising stock prices. Seeing everyone running to buy more stocks for their portfolio has me on edge. We could see a strong wave of fear/selling hit the S&P 500 index over the next two weeks, catching the masses with their hand in the cookie jar ... again. If you don't know what the CBOE's volatility index (VIX) is, then think of it as the fear index. It tells us how fearful/uncertain investors are or how complacent they are with rising stock prices. Additionally a rising VIX also demonstrates how certain the herd is that higher prices should continue. The chart below shows this fear index on top with the S&P 500 index below and the correlation between the two underlying assets. Just remember the phrase, "When the VIX is low it's time to go, When the VIX is high it's time to buy." Additionally the volatility index prices in fear for the next 30 days, so don't look at this for big-picture analysis. Fear happens very quickly and turns on a dime, so it should only be used for short-term trading, generally three to 15 days.