The principles of Indian Classical Music are well explained by these 40 principles put together by Pt Bhatkhande.
1. The ShuddhaSaptak (The basic scale) is taken as BilawalThaat. 2. All the raags are divided based on the number of notes in the Aaroha and Avaroha as Audav (Raag of 5 Notes), Shadav (Raag of 6 notes), Sampoorna (Raag of 7 notes). 3. A raag cannot have less than 5 notes (out of 12 notes including komal and teevra). 4. The combination of Audav, Shadav, Sampoorna in the aaroha or avaroha make 9 types jatisof raag based on the number of notes in it. 5. Each raag is based on a thaat, and has Aaroha, Avaroha, Vaadi, Samvaadi, Samay, Ras, Thaat. 6. A samvaadi is always fourth or fifth from the vaadi. If vaadi is in the poorvangasamvaadi will be in the uttarang and vice versa. 7. By changing the vaadiswar a morning raag can be changed into an evening raag. 8. To enhance the beauty of the raag a vivaadi note can be used very rarely. 9. Each raag has a vaadi. The raag is identified as a poorvaraag or uttarraag based on the vaadi note. 10. Raags can be classified into 3 categories : o Raag with Komal Re, KomalDha o Raags with Shuddha Re, ShuddhaDha o Raags with KomalGa, Komal Ni Normally in the Pratahkaalinsandhiprakashraag, Re and Dha are never absent. And in SayamkaalinsandhiprakashraagGa and Ni are normally not absent. 11. Ma indicates whether the Raag will be sung at day time or at night. 12. The raags with KomalGa, Ni are performed at afternoon or at mid night. 13. After the Sandhiprakaashraag mainly raags with Re, Ma, Dha, Ni shuddha are performed. 14. Sa, Ma, Pa are the important notes in raags of 3rd prahar of day and the night. 15. Teevra Ma is found mainly in Raags of the night. It's found rarely in the day time raags. 16. If the vaadi is one of Sa, Ma, Pa, that raag can be sung at all the times. 17. Ma and Pa can not be simultaneously absent from a raag. 18. Each raag must consist of the note Sa. 19. No two forms of the same note are taken one after the other in a raag. There are exceptions such as RaagLalit though, to this rule. 20. The raag's beauty is enhanced more if sung at the designated time. 21. Teevra Ma and Komal Ni come together very few times. 22. The raags in which both the Ma appear are similar in nature. The aaroha is different but the avaroha is quite similar. 23. In the raags sung at 1st prahar of the night, and which have both the Ma, Shuddha Ma is taken in both aaroha as well as the avaroha but Teevra Ma is taken mainly in aaroha. 24. In raags of 1st prahar of the night aarohi Ni and avarohiGa are Vakra. Ni in the avaroha is not emphasized. 25. In Indian classical music as opposed to the Karnatak classical music, the swar is more important than the Taal. 26. The poorvaraag show their special characteristics in the aaroha, where as the uttarraag show their special characteristics in the avaroha. 27. Each thaat can produce poorva and uttarraags. 28. In the raags of the serious, calm nature Sa, Ma, Pa seem to have a prominent place. They are more effective in the MandraSaptak. Whereas in the raags of light mood, this is not found to be so. 29. While entering from one thaat into another thaat, Para Mel Praveshakraags (raags on the border of the two thaats) are rendered. 30. The sequence normally followed is sandhiPrakashRaag then raags with Re Dhashuddha then the raags with Ga, Ni komal. 31. SandhiPrakashRaag invoke Karun ,Shantras. The raags with Re, Ga ,Dhashuddha invoke Shrungaar and Hassyaras. The raags with KomalGa, Ni invoke Veer, RoudraRas. 32. The raags which have Komal Ni normally have Shuddha Ni in the aaroha. For example Kaphi and Khamaj. 33. When two to four notes are together they cannot be called a raag . They can at best be called a taan. 34. In raag notes can be prominent, or insignificant (insignificant does not mean absent though). 35. After twelve at night and twelve in the morning Sa, Ma, Pa start assuming importance gradually. 36. In the raags sung in the afternoon, Aaroha either does not consist of Re and Dha or they are insignificant. In these RaagsGa and Ni really shine with full glory. 37. The raags with Sa, Ma, Pa as Vaadi are of serious nature. 38. In the dawn time raagsKomal Re and KomalDha are predominant and dusk time raags have the prominence of ShuddhaDha and Shuddha Ni. 39. The combination NiSaReGa immediately establishes Dawn - Dusk time raag. 40. Poorvaraags are more elaborate in the aaroha and uttarraags are more elaborate in the avaroha.