Anybody who has tried to do this knows just how hard it really is to realize. There are lots of different meditation techniques that can be used to realize this form of mental rejuvenation and raise grey matter.
When they replicated the Sanskrit letters, they established themselves in a state of unity with development during its very source. This was enough to affect grey matter in the mind and raise cortical thickness.
Theta is the kingdom of your subconscious mind. It’s also known as the twilight state because it is typically only briefly experienced as you drift off to sleep (from Alpha) and arise from deep sleep (from Delta). A feeling of deep spiritual link and oneness with all the Universe might be experienced at Theta.