As Usha Goswami made clear (see my post 'Research on reading') written language is a representation of spoken language. In other words, written language was invented to stand for the sounds in speech. Wherever you go in the world, humans speak and listen. However, not all societies possess writing: they simply don’t have writing systems to represent their languages. Peter T. Daniels puts it like this: 'Humankind is defined by language; but civilization is defined by writing. Writing makes historical records possible; and writing was the basis for the urban societies of the Old World. All humans speak; only humans in civilizations write, so speech is primary, and writing is secondary.' Daniels, P.T. and Bright, W., (1996), The World's Writing Systems, Oxford, OUP.
In order to think about how to teach reading and spelling, it is worth thinking carefully about the relationship between speaking and writing. For writing to work, it is necessary to represent the speech sounds of a language. To paraphrase Daniels, writing is a system of more or less permanent marks used to represent speech in such a way that it can be recovered quite accurately without the intervention of the speaker. ('The Study of Writing Systems', in Daniels and Bright, p.3) It does not matter how many writing systems have been invented, the point is that for complete functionality they must represent the individual speech sounds of the language they encode.
It was no coincidence that the development of writing ran parallel to the development of more complex societies. To keep records of business and rudimentary forms of government requires accurate recording systems. Arriving at the idea that ALL words in any language could be represented using arbitrary symbols representing individual speech sounds enabled people to keep accurate and complex records. In addition, it offered those who could read and write this invented code the possibility of sending accurate messages over vast distances, as well as keeping records for posterity.
Most European languages are alphabetic and relatively transparent: meaning that, for example in Spanish or Italian, most sounds are represented by just single-letter spellings. This makes them easy to remember and results in most children learning to read and write quite quickly. The problem with written English is that it does not have this simple transparency. In fact, English has one of the most complex alphabetic codes, thereby requiring very careful and accurately sequenced teaching.
What seems to have passed unnoticed by the English-speaking educational establishments, both historically and currently, is that in order to teach ALL children to learn to read and spell successfully, an appropriate teaching methodology has to be developed based upon both an understanding of the English alphabet code itself and knowledge of child development and learning theory - not, as in traditional 'phonic' approaches, a top down analysis founded on what literate adults mistakenly believe might have been the processes they went through to achieve their own literacy. Teaching a child that the marks on the page that we call spellings (letters or combinations of letters) stand for the sounds in their speech makes the system immediately accessible and roots it in everyday experience. Of course, as with any kind of skilled behaviours, reading and spelling need to be learned systematically, starting with the simplest concepts before moving on to the more complex ones.