Brief Introduction to 3 Gunas

The creation comes into existence with the emergence of the 3 gunas or qualities — Sattva, Tamas and Rajas.

Sattva is intelligence or knowledge.

Tamas is matter, the substance of creation.

Rajas is the putting together energy.

Metaphorically, to build anything (like a house), you need knowledge of the house (how it's to function, etc). Material. And movement or energy to sculpt the material according to the knowledge.

Thus from standpoint of the universe, in the presence of the three gunas — creation, sustenance and change (destruction) takes place. In fact, these three phenomena is observed in any facet of life. 

Right now, new cells are being created in your very body. They're being sustained for a while. And will soon be replaced by new.

Thus the three gunas are inseparable as they're required for operation of anything. 

The combination of gunas also sculpts you, the person. Hence infinite personalities and objects throughout our cosmos — just like the combining of RGB colors, producing 16 million combinations.

While under spell of ignorance of real nature of “I”, which is free of the gunas, the individual carries a deep belief that “I am doing all this”. Yet it's the gunas that are doing the entire universe. 

Upside and Downside:

All 3 guṇas have an upside as well as a downside.

Rajas is the active, creative force. It is the mode of passion and desire. Not all desire or passion is unconstructive however. For example, you need a passion for self inquiry and a strong desire for liberation.

Tamas is the very substance of matter, a heavy and steady energy. Without Tamas, you would not be capable of endurance. You would not be ‘earthed’ and would never be able to sleep.

Sattva is a valuable energy for inquiry and should be cultivated as it is the guna most conducive for self-knowledge to take place. With excess sattva, there is danger of experiential bliss, a common trap in spiritual world.