On taking parivraja and leaving Kapilvastu like the sages of the Upanishads, Siddhartha practiced yoga and meditation. At Vaishali to learn meditative concentration he studied with Alara Kalama, who was said to have had hundreds of disciples. Siddhartha soon learned how to reach the formless world, but still having mental anxieties he decided not to become a disciple of his first teacher Alara Kalama. Nor did he become a disciple of his second teacher, Uddaka Ramaputra, after he attained the higher state of consciousness beyond thought and non-thought.

Still not satisfied Siddhartha decided to practice the path of extreme austerities, and in this quest he was joined by the sage Kaundinya and four others. He pressed his tongue against his palate to try to restrain his mind until the perspiration poured from his armpits. He restrained his breath and heard the violent sounds of wind in his ears and head. He went into trances, and some thought he was dead. He fasted for long periods of time and then decided to try limiting his food to the juice of beans and peas. As his flesh shrank, the bones almost stuck out of his skin so that he could touch his spine from the front; after sitting on the ground his imprint looked like a camel's footprint.

For six years Siddhartha practiced such austerities, but instead of achieving superhuman knowledge and wisdom he only seemed to get weaker and weaker. Finally he thought that maybe there was a better way to attain enlightenment. He remembered how while his father was working he used to sit in the shade of an apple tree free of sensual desires. Perhaps in concentrating his mind without evil ideas and sensual desires he should not be afraid of a happy state of mind. However, to gain the strength he felt he needed for this concentration he decided to start eating again. When he gave up practicing the extreme austerities, the five mendicants who were with him became disillusioned and left him, saying that Gautama lives in abundance and has given up striving.

Siddhartha reasoned that a life of penance and pain was no better than a life of luxury and pleasure, because if penance on earth is religion, then the heavenly reward for penance must be irreligion. If merit comes from purity of food, then deer should have the most merit. Those who practice asceticism without calming their passions are like a man trying to kindle fire by rubbing a stick on green wood in water, but those who have no desires or worldly attachments are like a man using a dry stick that ignites.