To solve the mystery, look to the source. Test your spelling knowledge of KS3 words beginning at so.
"Science cannot solve the ultimate mystery of nature. And that is because, in the last analysis, we ourselves are a part of the mystery that we are trying to solve." - Max Planck.
If the world is a mystery, and human beings mysterious because they are part of that world, is it any surprise that a human production such as language is also mysterious? If you find spelling easy, then very well done! But if you find it difficult, try not to despair.
The more familiar you grow with words and the variety of rules which govern their spelling, the more strange language can come to seem. The English language is old and has developed over many centuries, recording many of these changes in its spelling. It is not phonetic, which means that you cannot reliably pronounce words by looking at their spelling, or spell them accurately by "sounding it out". There are also multiple correct ways to spell certain words at any one time, for instance, words which have an -ise ending, such as "organise" can be spelled equally correctly with an -ize ending (i.e. "organize"). It's a great deal of work to keep track of all of this information, so don't be fooled into thinking that spelling English ought to be easy!
One thing that does help with spelling is practice, so have a go at this quiz.