The world’s most extraordinary book of practical philosophical idealism of India is Yoga-Vasishtha*.
The gist of this work is this:
“The non-dual Brahman or the immortal soul alone exists. This universe as universe is not. Knowledge of the Self alone will free one from this round of births and deaths. Extinction of thoughts and Vasanas is Moksha. Expansion of mind alone is Sankalpa. Sankalpa or thought, through its power of differentiation generates this universe. This world is a play of the mind. This world does not exist in the three periods of time. Extinction of Sankalpas is Moksha. Annihilate this little ‘I’, Vasanas, Sankalpas, thoughts. Meditate on the Self and become a Jivanmukta.”

Swami Sivananda

See The Yoga Vasishtha

* Here you can download the Yoga Vasishtha Laghu