Time is the most powerful aspect of knowing the market actions. The one who studies the history can figure out how past will repeat itself.
Most of the Gann researchers & traders have ordinary thinking & stand on time. They try to use the Time to find a particular Date or Bar on a chart where Price can have Top or Bottom.
Through my Two decades of research, I have gained Knowledge that Time is the principal factor.
But not just for finding a particular Date or Bar on chart; but also for identifying the coming market move.

It is GOLD & not known by many so-called experts.
As my years of research has confirmed me, that Mr. Gann gave Clue in the above quote on use of Time.
For understanding his Precious knowledge, first one needs to figure out the truth of Gann. And then it requires deep experiments for confirming the conclusion.
After many years of hard work & research, I discover the harmonious relation of Price movement with time.
Gann is conveying the same point in his quote, but secretly.
Many researchers misinterpreted the Gann words, and they had formed the wrong viewpoint.
Gann’s books, courses & research papers are Gold mine of Priceless knowledge. His work is far better than Unreal software & indicators.
Mr. Gann had other insights also, along with the Date factor.
He applied all that to Time the market moves. That will complete the broad understanding of his quote.
You can learn his Precious trading secrets. In my courses, you will learn in-depth correlation of Time & Price.
That all will help you in locating the important turning points of the market, which are Ten times better than half-baked Knowledge of dates & bars.

The above Dow Jones Industrial Index Chart of 1929 is showing the value of Time. By picking up the Location where Trend shifts & market gets crashed.
For self learning, you need to dig deeper. And need to spend somewhere around 10-15 years for understanding the Gann’s thinking & work.