differences bet.writing and speech

however ,aside from the fact that speech is uttered and heard ,writing is written and read,there are some difference between writing and speech that would show that speech,not writing is basic to language

writing is a relatively recent invention.while people have most likely been speaking since the beginning of human society hundreds of thousands of years age, the most ancient preserved examples of writing are only about 7,000 years old.

writing is much less widespread than speech.many languages even today exist only in spoken form.
people generally start speaking during the first two years of life. The ability to speak is automatic and is probably inborn rather than learned.writing,however, has to be consciously learned and typically builds on speech ability.

writing is a reflection of speech,all writing systems are based,in one way or another,on the sound systems they represent;a particular sign or letter always represents some unit of sound in the spoken language. it is never the case that the sound system of a language is based on a particular system of writing.

Trivia...

       did you know that......

                              In England, the Speaker of the House is not allowed to speak.

while the rules on grammar tend to be stricter and more formal in writing than in speech, do not disregard these rules when you communicate through speech.After all, the main goal of having rules on grammar(and studying them)is for you to be better understood and you want to be understood by speaking as well as by writing.