The holy mantras are generally given to the disciples by the guru and it is generally followed traditionally. The purpose was to make the persons who recite the mantras be disciplined and recite it with devotion. So they were usually kept secret. But later it became that only some sections of the society got access to the mantras.
rAmAnuja was taught the nArAyaNa mantra by his guru and told him that it is very secret if he reveals it he will go to hell. After getting the mantra he went to the top of the temple tower and shouted loud to collect the people there. He then told the mantra to all loudly and asked them to chant. His guru got angry and asked him why he did this even after knowing that he will be going to hell if he reveals it. rAmAnujA said humbly, "If I alone chant the mantra then I only will go to vaikuNTha but if I tell to everybody all can go to vaikuNTha and even if I go to hell I can be happy that all others are going to vaikuNTha". He breaks the barriers on the accessibility of the mantra.
Shiva mahA purANam while the holy mantras are described says that they have to be said only to true devotees and it doesn't say that only some sections of the society can say them (especially the holy five letters ). Anybody can chant the holy five letters at any time, preferably always as much as possible. It is the love for the Lord that matters. mANikka vAchakar proclaims in his thiruvAchakam, "The Lord is showing His grace to His devotees, all of you come and hurry !!".
Posted on: 9.8.96