While memorizing it I had to struggle with many demonic obstacles, but then after a while they were all gone and I figured the demons realized that I was weak and that I really didn't know how to use the mantra so they lost interest and didn't bother to test me anymore. Because of this I started to doubt that I used the mantra correctly, thinking about the possible need to receive teachings or transmission of some sort directly from a living teacher in order for the mantra to have any positive effect. After a while those doubts made me quit using the mantra.
In his Awakening of the Faith Treatise, the Patriarch Asvaghosa (first century) admonished:
"There may be some disciples whose root of merit is not yet mature, whose control of mind is weak and whose power of application is limited -- and yet who are sincere in their purpose to seek enlightenment -- these for a time may be beset and bewildered by maras and evil influences who are seeking to break down their good purpose.
Such disciples, seeing seductive sights, attractive girls, strong young men, must constantly remind themselves that all such tempting and alluring things are mind-made, and, if they do this, their tempting power will disappear and they will no longer be annoyed.
Or, if they have visions of heavenly gods and Bodhisattvas and Buddhas surrounded by celestial glories, they should remind themselves that these, too, are mind-made and unreal.
Or, if they should be uplifted and excited by listening to mysterious Dharanis, to lectures upon the paramitas, to elucidations of the great principles of the Mahayana, they must remind themselves that these also are emptiness and mind-made, that in their essence they are Nirvana itself.
Or, if they should have intimations within that they have attained transcendental powers, recalling past lives, or foreseeing future lives, or, reading others' thoughts, or freedom to visit other Buddha-lands, or great powers of eloquence, all of [these] may tempt them to become covetous for worldly power and riches and fame.
Or, they may be tempted by extremes of emotion, at times angry, at other times joyous, or at times very kind-hearted and compassionate, at other times the very opposite, or at times alert and purposeful, at other times indolent and stupid, at times full of faith and zealous in their practice, at other times engrossed in other affairs and negligent.
All of [these] will keep them vacillating, at times experiencing a kind of fictitious samadhi, such as the heretics boast of, but not the true samadhi.
Or later, when they are quite advanced [they] become absorbed in trances for a day, or two, or even seven, not partaking of any food but upheld by inward food of their spirit, being admired by their friends and feeling very comfortable and proud and complacent, and then later becoming very erratic, sometimes eating little, sometimes greedily, the expression of their face constantly changing.
Because of all such strange manifestations and developments in the course of their practices, disciples should be on guard to keep the mind under constant control.
They should neither grasp after nor become attached to the passing and unsubstantial things of the senses or concepts and moods of the mind.
If they do this they will be able to keep far away from the hindrances of karma."(Wei-tao, tr., in Goddard, A Buddhist Bible. p.402-403)
Do you know if it is useful to recite the Shurangama mantra even without having received teachings or transmission on it from a living teacher?
Since 1998, when I picked up books and audio teachings of the late VM Hsuan Hua, this Mantra has been my practice besides a few more and no, I do not have any personal teacher or what not but I can personally attest to its efficacy in my life's myriad situations (best not discussed in a public forum).
All I did was to use a sincere and consistent mind to recite it firstly as a means to aid my cultivation and end my birth and death issue and secondly for the benefit of all sentient beings.
http://www.siddham.org/yuan_english/sha ... 30101.html
The Shurangama Mantra is the most important of all mantras.
It is the entire substance and function, and includes all the doctrines of the Buddhadharma.
In general, the mantra contains dharmas of auspiciousness.
This means that when you recite the Shurangama Mantra, everything goes just as you'd like it to.
It's really lucky and extremely auspicious.
The advantages of the mantra are so many that one could not even begin to express them in several years time.
(Parable 94 & 96)
"Therefore, the cultivator should remember:
when the mind is still, all realms are calm; when delusion arises, demons are born."
"Everything is Mind-created. Once the mind is reformed, evil karma disappears."