Did the Buddha ever delve on the dangers of one's own spirtual achievements feeding the ego? This question came up when I really thought back on both my and many others' spiritual journey. In the New Age community, especially, the sense of viewing things as illusions and making progress in one's spiritual path can easily steer you to be more condescending or arrogant (i.e viewing others as somehow lesser or more immature than you) and in the process, feed the Ego. 

Often you see this in spiritual teachers as well, who seemed to have, in their journeys to eliminate the Ego, fueled their Ego.

Did the enlightened Buddha ever touch on this subject?
There is one good example of the Buddha delving on the dangers of one's own spirtual achievements feeding the ego.  It is that of the erudite monk called Potila. Buddha dismissed him with just one word “THUCCA POTILA”  (meaning empty Potila), because he only taught others, but did not practice. It was his EGO that prevented him from achieving even the level of a stream entrant. The story is best described in THIS BLOG.


  During the time of the Buddha there was a bhikkhu named Pötila, who was well-versed with deep Dhamma concepts and was a well known teacher; he had developed abhinna powers as well, but had not attained even the Sotapanna stage. His desanas (discourses) were deep and only those at the Anagami stage (at least Sotapanna stage) could follow them and get to Arahanthood. One day he went to see the Buddha, paid respects, and told the Buddha that he had been a Dhamma teacher during the times of several earlier Buddhas too, and helped many to attain Nibbana (Arahantship).
  
  The Buddha asked him whether he has attained any magga phala and Bhikkhu Potila admitted that he had not. The Buddha just commented: ”Thucca Potila” and turned his attention to other matters; thucca (pronounced “thuchcha”) in Pali means despicable or “lowly”.
  
  So, bhikkhu Potila, who had expected praise from the Buddha for helping others, realized that he needs to work on his own salvation before helping others. He strived by himself and could not make any progress; he was trying very hard to “give up all attachments”, following the same instructions he was giving others. But no matter how hard he tried, he could not succeed.
  
  When he sought help from other bhikkhus, they were reluctant to become his teacher because everyone knew he was very knowledgeable in Dhamma. Eventually, he went to this very young Arahant, who was well-known for his teaching abilities, and sought help. The young Arahant agreed to help, only if bhikkhu Potila agreed to carry out everything as instructed, and Potila agreed.
  
  The young Arahant decided to use an unusual kammatthana (instructions). He took Potila to a large area covered by mud, and asked him to wade into the mud and keep going until told to stop. Potila started wading in mud and kept going until he was told to stop when the mud was all the way up to his chin; he was barely able to move at this point because mud was heavy.
  
  The Arahant told him that, “if someone is stuck in mud like that any knowledge about cleaning oneself by taking a bath is not going to help. One needs to get out of the mud first”.
  
  Then he asked Potila to come back. Potila had great difficulty in moving forward initially, since he was all the way up to the chin in thick and heavy mud. While dragging himself out of the mud with great difficulty, Potila realized what the young Arahant was talking about. It is not possible to get out of mud until one realizes that one is stuck there, and getting out of mud required sheer will power. Similarly, he had not realized that he was stuck at a much lower moral level; he needed to cleanse his mind first.
  
  The “giving up” part comes with a mind that has removed the wrong visions (micca ditthi); and that comes via comprehending anicca, dukkha, anatta. If someone at a level below at least the Sotapanna stage, “giving up worldly things” is not possible; that could easily lead to patigha or “friction” or “anger with oneself for giving up things”. One’s mind has not advanced to that stage yet.
  
  The simile can be made even better by looking at what happens to ants who get stuck in honey. Here unlike mud, the sense pleasures are appealing and there is no incentive to get out either. Those ants who get stuck in honey, would not even try to get out because they are too busy enjoying the honey. Even when they are barely stuck, and can move out of honey, they would not because they like the taste of honey. Just like that, any living being, whether a human or even the lowly worm, likes to indulge in the sense pleasures, and thus gets stuck.
  
  And even when one realizes that one needs to get out of “the honey pot” it is hard, at least initially.
  For that one needs to see the perils of staying in this rebirth process, where birth in lower four realms will lead to unimaginable suffering. Even if one can strive to be born in higher realms, that will not last long. This is “anicca“: no matter how hard we try to find refuge in the 31 realms it is not possible to do so in the long run.
  
  With much effort, Potila slowly made his way up to the waist level, and started feeling the lightness of being free of mud. He could now move faster too. He felt the relief when he was out the mud, and was asked to go and take a shower. Now, cleaning up with soap could be done; but while stuck in mud, there was no use of soap and water. Just like that the deep Dhamma that he had memorized was of no use to him while he was still stuck in mud.
  
  Eventually, when one comes out the mud that is like the Sotapanna level. One is still covered with mud, i.e., one still likes to enjoy sense pleasure. But now one KNOWS that one needs to take a shower, use soap and shampoo, and remove all that mud.