Spiritual Transformation is a new concept in the field of spirituality, Eastern or Western. The Spirit is to detach itself from life and seek its origin which is moksha. The Upanishads had laid down that all in creation is Spirit and is of Spirit -- Sarvam Brahman. But in practice, they have shunned life and sought moksha.
Sri Aurobindo takes the vision of the Upanishads to its logical conclusion. Mind, life and body are made of Spirit according to the formula of the Upanishads. So, Sri Aurobindo says we must not shun them but accept them - mind, life and body - and discover the Spirit they really are. His thesis is Life is of Spirit, but the Spirit there is buried. If we encourage the hidden Spirit, it will come to the surface. That is what I call invoking the Spirit. The buried Spirit is the immutable Spirit, it does not change. But the life we live - our daily lives - is Spirit in disguise. Externally it is Force - Shakti - but below the Force it is the Being or Spirit. Force is subject to limitation, to karma, not the Spirit below. Now it is up to us to encourage the Force or encourage the Spirit.
It is left to our choice. If you are an officer and a customer visits you, you have two options -- 1. welcome him with a broad pleasant smile, offer him all help from his point of view, or 2. without looking at him, take a bureaucratic attitude, wait for him to talk and give brief No's as answers. In the first choice, your Spirit emerges on the surface, meets his own spiritual attitude, life expands, work flowers and creates an atmosphere of harmony and progress. The second choice is a cold, stern, asserting, hard attitude of ego that prevents the Spirit in either of you from emerging. It also creates an attitude of human atmosphere that ensures that your spirit can never come out on the surface.
Every act, every moment contains these two options. To bring the Spirit to the surface of life all the time is to accept life in yoga. To do so in the Mind, Life and Body is Spiritual Transformation. It is a process by which the buried Spirit is activated to evolve as Mind, Life or Body. Such evolution is that of the Evolving Soul, the Psychic Being.