Can you trust what you see in meditation?

I recently posted an article about the significance of entering into altered states of consciousness for a Buddhist practitioner. I commented that sitting meditation tends to be heavily emphasized by Chinese Ch’an practitioners. Although Buddha himself had practiced Samatha meditation (which is pre-Buddhist) under various masters, he found it unsatisfactory. Samatha means calmness or tranquility. Eventually, Buddha came up with his own way of meditation, which he called Sati, which means remembering to observe. Sati, commonly known in the West as the practice of mindfulness, is essentially based on the Four Foundations of Mindfulness–mindfulness of (a) body, (b) feelings, (c ) mental states (citta), and (d) mental objects. In the Satipatthana Sutta, Buddha advocated the mindfulness practice as “the only way for the purification of beings, for the overcoming of sorrow and lamentation, for the destruction of suffering and grief, for reaching the right path, for the attainment of Nibbana.”

Buddha was quite aware of the calming effects of Samatha meditation. But in his sermon to Pukkusati, as recorded in the Dhatu-vibhanga Sutta (MN 140), Buddha noted that even if the meditator reaches the highest realms in Samatha meditation, where there is tremendous equanimity, the meditator will still be creating mental illusions.