This post is an advance topic but it is important to read, even for beginners in Buddhism. This is because when we practice Buddhist meditation, we want to avoid attaining non-Buddhist attainments (外道）. Only Buddhist attainments can free us from the chains of rebirth.
I learned this topic when I was sixteen years old and like most, I did not know what the monk was talking about. That is because I have not experienced meditations and its various stages of mental bliss and development. However, this knowledge equiped me with some cautionary ideas and later on in my life, it helps me identify questionable meditation techniques and teachers.
Remember, a person wearing Buddhist costume may be teaching you something that is non-Buddhist too. This is because they treaded the wrong way or arrived at a wrong stage, mistaking themselves to be enlightened. Or mistaking their method to be Buddhist. As advised by Buddha, equip ourselves with knowledge and there will be a time when you hear something and then goes “are you sure that is Buddhist?”
Foremost, it is important to understand Buddhist cosmology. Some of the higher heavens are attainable only through meditative achievements, but such heavens are not Nirvana and Buddhist should avoid them.
Therefore, if we attained something similar during meditation, we will know that it is not enlightenment. Likewise, if we hear any Buddhist teachers teaching attainments that sounded like those heavens, we know something is off.
Foremost, attaining the Sphere of neither perception nor non-perception is not enlightenment. This is a state where perception ceases but one is not dead or comatose. It is a deep meditational trance and was taught by Buddha’s second formal meditation teacher. Buddha had 2 formal meditation teachers. Buddha attained the same level as his teachers and then decided that those attainments are not enlightenment. This is one of them.
Next is the Sphere of Nothingness. This is where one maintained a mental view that everything is nothing. Buddha attained this level from His first meditation teacher and it was being rejected by Buddha too. Again it is not enlightenment and some Buddhist practitioners who contemplate Emptiness incorrectly as nothingness, inevitably falls into this trap.
Then we have to beware of Sphere of Infinite Consciousness. This is a positioning of mind as infinitely pervasive. I notice this is gaining traction amongst Buddhist in recent time and possibly because of western influence advocating mind is all-pervasive or everywhere. Perhaps people are simply substituting the word God with mind. In Buddhist practice, such mental positioning is not enlightenment. In short, although there is a saying that God is everywhere, Buddhist should not train their mind to achieve that state of being.
Sphere of Infinite Space. If you think that Buddhist Emptiness means an infinite blue space or black space or what ever space imaginable, please be very careful that you may be positioning yourself for rebirth in one of the formless heavens. This is not enlightenment too. Some Buddhist practicing Emptiness meditation may end up practicing this wrong path too. This usually arise because the word emptiness cause us to misinterpret it as nothingness.
The above are more relevant for advance meditator or Buddhist who practices Mahayana and Vajrayana meditation. (Due to the term emptiness being misunderstood) I am not enlightened but hope that parroting what I heard from monks can help spread the Truth.
And for beginners who read till here, congratulation! Just keep this knowledge in your mind. If you start serious mental training one day, these road signs will keep you safely on the right track.
Lastly, for Theravada meditators, let us bring our mind inwards to realize non-I first. That will automatically lead to higher attainments,
May all be well and happy.