In the empty eyes looking up at the blue sky, people can't help thinking. In distant ancient times, our ancestors looked at the blue sky and wanted to dye white cloth as beautiful as the blue sky in a way to make clothes more beautiful. According to historical records, in the Neolithic Age, working people in China discovered a kind of blue grass with red flowers in the wild. If you pick a leaf and rub it in your hand, its yellow-green juice will dye your fingers red and instantly turn into beautiful blue-green. If you rub the fabric with its fresh leaves, it will be dyed blue, so someone has collected blue grass for dyeing since then.

Later, people found that this kind of wild blue grass rubbing dyeing had some shortcomings, especially the thin and soft fabric like silk, which could not stand this rubbing. So someone soaked it in warm water to dye it. As early as more than 3000 years ago, our ancestors had dyed with blue grass. When dyeing flax or other plant fibers, lime is also added to the dyeing solution to increase its alkalinity, so that the dyeing effect of the fabric is better.

According to the record of "bluegrass palmatum, a local official in Zhou Li", a man named Xun Kuang summed up the experience of printing and dyeing production technology at that time? Put forward the philosophical famous saying that "green is taken from blue, and green is blue". "Green" and "cyan" also; Blue refers to the blue grass that makes indigo. Indigo is specially used to dye cyan, but the dyeing effect is far more than the original blue grass. Xun Kuang used this vivid example to illustrate his simple materialism in the practice of printing and dyeing production, and showed that everything in the world is constantly changing, developing and advancing.

At present, we are carrying out the new long March of "rejuvenating the country through science and education", and we need to draw a blueprint for the four modernizations. In the process of realizing the four modernizations, we should strive to climb new heights and step into the era of scientific and technological information as soon as possible. Students surpass teachers, apprentices surpass masters, young people surpass old people, and future generations surpass their predecessors. This is by no means a strange theory, but an inevitable law of historical development and a requirement of the times. China is a developing country, and its science and technology and national economy are still very backward. As long as we adhere to the party's line, principles and policies, the whole country will unite as one to carry out the four modernizations. First, in the near future, we will catch up with the advanced world level and stand among the world. Knowledge is shallow, as long as you think you are wrong and study hard, you can turn to the opposite side; And if I was ignorant, I thought everything was ready for me. Although this kind of green is taken from blue, it will never be green.