Sutra:
237. maRRai upAyangaLukku nivruththi dhOsham; idhukku pravruththi dhOsham.

Sri PBA Swami's Sarartha Deepikai:
In order to show that this siddhopaya will not tolerate any activity of the chetana, the difference between the other means and this means is now being showed.

For the other means, the activity of the chetans is required for them to exist and work. Therefore, if his effort fails, then they will fail. For this means, since it will not tolerate any other means, any effort of the chetana itself will make it fail.