This confused mixture of various writing styles, whose choice was dictated by genre and purpose, changed only somewhat over time. In summary, we may say that there were two main streams of writing styles, one best termed Chinese and another Japanese. Note that the Japanese spoke only Japanese, so the writing style that more truly reflected it in any given historical period was not Chinese, since it is believed that few Chinese compounds were used in daily conversation. When people set down their thoughts, however, they went into the writing mode of language use, which normally meant using more Chinese vocabulary and adding appropriate Chinese syntax to their writing. This gap between the spoken and written modes of language still remains quite large today, much wider than one would find, say, in English or French.
The Japanese did try to bring written Japanese closer to spoken Japanese for the first time during the Meiji period (genbun'itchi movement). Proposed in the first years of Meiji by such advocates as Maejima Hisoka (1835-1919) and later joined by scholar Kanda Takahira (1830-1898) and writers Yamada Bimyō (1868-1910) and Futabatei Shimei (1864-1909), this movement gained political momentum. Its development was spurred by the government's decision to adopt spoken Japanese as the main style of exposition in school textbooks beginning in Meiji 36. By the Taishō period (1912-1925) newspapers began to write their editorials in this spoken style.
During the Heian period (794-1185), writing began to indicate the voicing of a consonant. What is meant by this term? An example will clarify. Consider /ka/ and /ga/. The consonants /k/ and /g/ are "homorganic consonants," that is, they are consonants produced at the same place in the mouth and in the same manner. They are different only in that /k/ is voiced and /g/ is not. The writing system, hiragana or katakana, did not indicate this voicing distinction in writing during its first stages; the reader was therefore required to know when to use the consonant /k/ and when not to use the voiced version /g/ from the larger context. In other words, /ka/ and /ga/ were written exactly the same way (if the reader already knows Japanese, this would be like writing か for both か and が in contemporary Japanese), even though the voicing difference could differentiate meaning. Why was voicing not indicated? Perhaps it was due to the fact that skilled users of the language can correctly obtain the missing information (voicing, in this case) from the surrounding contextual information (Sklled Englsh rdr cn rd ths sntnc.) During the Heian period, however, one or two dots were written next to a character to mark the voicing of the consonant, to make clear in some ambiguous cases of pronunciation. The double dots for marking voicing came to be more commonly used in the Edo period (1603-1868).
Along the same line, the writing system began to make use of a small diacritic circle to indicate a change from /h/ to /p/, which became widely adopted in the second half of the Edo period in such popular publications as kibyōshi, ninjōbon and other types of popular writing (gesaku). For instance the moras /pa pi pu pe po/ are each written by adding a small circle diacritic to hiragana or katakana /ha hi hu he ho/ respectively (ぱぴぷぺぽ and パピプペポ). One might wonder how the consonant /h/ is related to /p/. The reason relates to the development of the consonant /p/, where /h/ is generally accepted to have come from /p/ by a process of weakening. One may say that this historical process is still exhibited in the writing system. For example, the counter for long cylindrical objects -hon in /ip-pon/, /ni-hon/, /san-bon/, where you can see /h/, /b/, /p/ alternate in pronunciation. Showing voicing in the writing system as well as writing the small circle diacritic is now a standard practice, except in calligraphic writing.