In the book Altered Traits by Daniel Goleman and Rachard J. Davidson, its says:
Sustained focus, the manual notes, brings the first major sign of progress, "access concentration," where attention stays fixed on the chosen target with wandering off. With this level of concentration come feelings of delight and calm, and sometimes, sensory phenomena like flashes of light or sense of bodily lightness.
"Acess" implies being on the brink of total concentration, the full absorption called jhana (akin to samadhi in Sanskrit), where any and all distracting thoughts totally cease. In jhana the mind fills with strong rapture, bliss, and an unbroken one-pointed focus on the meditation target.
The Visuddhimagga lists seven more levels of jhana, with progress marked successively subtle feeling of bliss and rapture, and stronger equanimity, along with an increasingly firm and effortless focus. In the last four levels, even bliss, a relatively gross sensation, falls away, leaving only unshakable focus and equanimity. The highest reach of this ever more refined awareness has such subtlety it is called the jhana of "neither perception nor nonperception."
In the time of Gautama Buddha, full concentration absorption in samadhi was heralded as the highway to liberation for yogis. Legend has ti that the Buddha practiced this approach with a group of wandering ascetics, but he abandoned that avenue and discovered an innovative variety of meditation: looking deeply into the mechanics of consciousness itself.
Jhana alone, the Buddha is said to have declared, was not the path to a liberated mind. Though strong concentration can be an enormous aid along the was, the Buddha's path veers into a different kind of inner focus: the path of insight.
I am deeply interested in the major difference between Jhana and the path of insight. Can you elaborate in simple words what could be those differences and benefits?