Pop music is mostly 3-minute songs. That's it (with exceptions). And, nowadays, mostly 'performed' without using musicians (or even produced by people incapable of playing one single note on any instrument - thanks to modern productions software). I don't say it's bad - because I enjoy also modern music. I just say it's different. Classical music is a whole world of different styles and has a lot more history than modern music. Furthermore, it is played by musicians who have worked years and decades to master their instruments. That's why, when you listen to a 'performance', it's so impressive when you know the amount of work and talent it takes for the musician (or orchestra) to master their instruments. From Bach to modern composers, from solo instruments to full-fledged orchestras, from melodic styles to totally wild experimentations... You have to listen, open your ears, feel and enjoy. Bach is considered mathematical (but for me, he's very emotional), and is seen as the grand-father of all modern music (listen to 'The Well Tempered Keyboard'). Bach has 'discovered' all harmonies possible using your current notation system. Anything you hear today in rock, pop, rap, ... you'll find these harmonies, melodic lines, etc... somewhere into one of Bach's works. You love movies? Listen to 'The Planets' by Gustav Holst and see the relation with 'Star Wars' music. A very interesting introduction to classical music is still the two 'Fantasia' Disney movies. You don't listen to classical music the way you listen to pop/rock/rap or jazz music. Classical music forces you to 'feel and think'. Some rock works relied heavily on using classical composers, some with good results, some not. Emerson, Lake and Palmer orchestrated Mussorgsky's Pictures at an exhibition for rock lovers. I could go on and on.
