Sometimes the simplest things turn out to be surprisingly useful.
Wyckoff's second law of cause and effect implies that price movement (up or down) should be proportional to the effort ( volume ) supplied. Price is not subject to gravity ; without volume it cannot move.
This one-line indicator acts a bit like a lie detector for price action.
It simply identifies bars with decreasing volume , the idea being that movement on a bar where volume has decreased is considered suspicious.
Falling volume accompanied by much price movement is more suspicious than it is on bars with less movement.
Pure luck would have it that the varying size of the orange mass on candlestick bodies provides an easy way to visually grasp the degree of suspiciousness their movement should be considered with because it is directly proportional to the body's size.
Taking things from the opposite perspective, this indicator reveals the more meaningful candles on your chart, the ones telling the truth, since their color is not changed if they are accompanied by rising volume .