Way Truth Light in Chinese / Japanese...

不比不知道一比吓一跳 is a Chinese proverb that literally means: [If one not does] not make comparisons, [one will] not know [the truth] when [one] compares, [one will be] greatly surprised.

This goes to the idea that if you do not know bad times, you cannot know what good times are.
...And...
You can not know light without experiencing darkness.

Another way to translate this would be: If you wish to be enlightened, you need to make comparisons and analyze every aspect (of a situation, issue, or problem).

道 is the character “dao” which is sometimes written as “tao” but pronounced like “dow” in Mandarin.

道 is the base of what is known as “Taoism.” If you translate this literally, it can mean “the way” or “the path.”

Dao is believed to be that which flows through all things and keeps them in balance. It incorporates the ideas of yin and yang (e.g. there would be no love without hate, no light without dark, no male without female.)

The beginning of Taoism can be traced to a mystical man named
Lao Zi (604-531 BC), who followed, and added to the teachings of Confucius.

More about Taoism / Daoism here.

Note that this is pronounced “dou” and sometimes “michi” when written alone in Japanese but pronounced “do” in word compounds such as Karate-do and Bushido. It's also “do” in Korean.

Alternate translations and meanings: road, way, path; truth, principle province.

Important Japanese note: In Japanese, this will generally be read with the road, way, or path meaning. Taoism is not as popular or well-known in Japan so Daoist/Taoist philosophy is not the first thing a Japanese person will think of when they read this character.

See our Taoism Page