I haven't really written about sattva, tamas and rajas, which are integral concepts to Ayurveda. They are mental qualities, which are acquired by the ego, personality, attachment, desire, imagination etc. Whilst the soul is immortal, the personality displays these different qualities, called guna. All three qualities are needed for life, but on the spiritual path we should develop sattva.
In England Babaji gave a talk explaining sattva, rajas and tamas very simply by relating the guna of characters in the Mahabhrata.
"Those who are selfish, wicked, enjoy harming people, prone to greed, anger, jealousy, robbing others, full of false-pride are described as tamasic ... the wicked character Duryodhana would fit into this description - always acting on his own selfish imaginations, supported by his father the king."
"The second type of ego, rajasic, is mainly concerned with personal glory, even though it might be in a noble way. Again in the epic, the characters of Bhishma who was noble and valiant, and Drona who taught all the princes the science of archery, could be described as rajasic. Even though they had many noble qualities, when it came to the famous scene when Princess Draupadi was threatened with public disrobing, they didn't protect her. They used excuses such as " I must always support the king", and comments like this. But they didn't simply do the right thing and stand up for a woman's honour in this situation, because they were more interested in their personal glory.
"...They knew what was right and what was wrong, but they didn't try to simply protect her when she was in trouble like this. Draupadi asked for Bhishma's help - he was respected by all in the court. Though he knew that this was wrong ... he didn't protect her, saying, "Without the king's order, I cannot protect you." This is rajas - acting for personal glory."
"This is how Lord Krishna worked - not for personal glory, but for the larger cause. Just like when the war in the story of the Mahabharata was going to start, Krishna announced that each side could have either Him, or His army - whichever they chose. But if they chose Him, He would not actively fight for that side. Arjuna was noble and devoted to Krishna, so he asked Krishna to be on his side and steer his chariot - even if He didn't fight. Hearing this the wicked Duryodhana said, 'Arjuna is an idiot. Now I have Krishna's whole army fighting on my side, while he has chosen to have only Krishna on his side - and Krishna will not be fighting for him at all.'"Krishna's satvic nature meant He was concerned with the larger cause. Thus at one point in the battle, He picked a wheel to use as a weapon to kill Duryodhana, simply for the sake of dharma (Righteousness). Seeing Krishna doing this, Arjuna told him, 'You said you wouldn't fight in this battle.' But Krishna replied, ' It is no problem. If I do this and kill Duryodhana, only my personal name and reputation will be damaged, but all the people of the kingdom will be benefited.' That is how a satvic ego behaves - for the larger cause.
Visit Babaji's website for more of his teachings.I'll write some more about the three gunas and how to develop sattva a little later.