Solemn Japanese and casual foreign words

Many people may think the Japanese is not a contact language, and it had been my opinion, too, till this morning. Now I know it is a contact language and the Japanese has a long history of coming to contact with foreign languages and accepted them.

For instance, the Japanese people did not have a written language until the 4th century. Till then, people memorized what was spoken and orally conveyed thoughts. In the 4th century, the country imported Chinese phonetic symbols and it was when the people were able to record what was discussed. An interesting thing is that the Japanese have invented two ways to pronounce Chinese characters: the Chinese way and the Japanese way. In short, a single character has two sounds.

If I recall what I learned during the compulsory education, Japanese people had given solemn values to the Japanese pronunciation and casual values to the Chinese pronunciation. This dichotomous use of words have continued till today.

If you live in Japan for some time, you may have noticed that the people will give a casual value to supermarket receipts, but a solemn value to "ryo shu sho," which is the Japanese word for receipts. If you buy something at a supermarket and wants to use the receipt for tax reduction purposes, you may go to the service counter and ask to replace the receipt with a ryo shu sho. This is a good example of having more value to Japanese words than to imported words.

My point is that the Japanese people use two sounds (one Japanese sound and the other foreign sound) to accept the use of foreign words. I would imagine the coexistence of the two sounds is the proof of the people's defensive posture against the use of foreign words, but the acceptance of foreign words to facilitate usefulness.