The most frequent piece of advice offered to stock market investors is that the trend is your friend. I first came across the axiom in a book published in 1972 by one of the pioneers of technical analysis, James Dines. Dines wrote that a trend in motion is assumed intact until it actually ends.As long as data and sentiment support the present course one might conclude that the collective evidence driving the trend can be trusted to continue. An uptrend is a rhythm of ascending highs and lows, connected with a line that is easily visible to the naked eye. A downtrend is the opposite (descending highs and lows) but equally apposite.If we learnt anything from the market last month, it was to stick with Dines's guiding philosophy. It was a bleak month, pressured by the unresolved Greek debt crisis, heaving Chinese equity markets, plunging commodity prices and the deep analysis of each word uttered by Janet Yellen in the hope of determining when the Federal Reserve would raise interest rates.The small half percent gain in the JSE's All Share Index masked bigger moves in the underlying sectors. The Industrial Index put on 1%, the Financial Index 3%, while the Resource Index shed a massive 8%, highlighting the challenges engulfing the mining industry. Beleaguered platinum miner Lonmin tumbled 50%. On the other hand, the JSE's most valuable company, British American Tobacco, advanced an impressive 15%.The current paths in the market appear set to continue, with weak demand and growing producer supply weighing on mining margins, while low oil prices and improving employment numbers in the US and Europe underpin a pick-up in spending.There is nothing to suggest that the charts pointing from the bottom left corner to the top right in companies like British American Tobacco, SABMiller and Bidvest, and even expensively priced Woolworths and Mr Price should progress differently. Nor is there a possibility that the downward passage (top left to bottom right) of mining counters like Anglo American, Kumba, Angloplats and Gold Fields should suddenly change direction.Yet there are still leading money managers who feel otherwise, and have taken large bets on major recoveries in the commodity markets. Of course it is logical that high-cost producers will be squeezed to reduce output, diminishing global supply. But the stock market is not a game of logic but of mass emotion. Dines advises that when the mood turns bearish, driving stocks lower, it's best to get out of the way promptly.As mining shares sink further, though, failure to acknowledge a poor decision becomes more difficult for investors. Knowing how to get out of an unfavourable situation takes courage. But ego is part of the human psyche and has probably cost more money than any other character flaw. Dines cautions that stubbornness leads investors to fall prey to emotional traps. He warns: don't ever make the mistake of telling the market it is wrong.Trends seldom continue forever but distinguishing the inflection point is a major challenge. Dines considers it simple. When good news no longer pushes a market up, or bad news no longer sends share prices reeling, it's time to re-evaluate your positions.Unfortunately, history reveals that commodity cycles take years to change path. In the meantime, for the persistent resource bulls, it's time to exercise patience and focus on those shares that are still sky-bound...