In studying Zen the important thing is “One mind unborn.” In reciting the buddha-name the important thing is that pure mindfulness [of buddha] be continuous.
Investigating the method of reciting the buddha-name, the intent is for wondrous awakening and birth in the Pure Land. When reciting the buddha-name, mind and buddha are clear and distinct.
When studying Zen, both [mind and buddha] are cut off. Because they are cut off, the power of Zen meditation gradually prevails, and the power of buddha-name recitation gradually weakens. So then, later on, how can one achieve both [Zen] enlightenment and birth in the Pure Land?
“One mind unborn” is Zen; it’s not “studying Zen.” Heightening mindfulness and subduing doubts is called “studying.” This is what the Surangama Sutra means with sayings like “Take this mind and investigate over and over again.
Both reciting the buddha-name and studying Zen involve mindfulness: there is no contradiction between them.