觀無量壽佛經義疏 3.129

3.129

「『觀世音菩薩及大勢至，於一切處身同眾生，但觀首相，知是觀世音、知是大勢至。』」身同眾生，即彼徒眾中下二輩形相全乖，諸大菩薩則有相濫。經云「眾生生者皆是阿鞞跋致，其中多有一生補處，其數甚多」等。但觀首相，可辨二聖，觀音冠有立佛、勢至髻有寶瓶。二、明隨侍以顯須觀。

"‘The bodies of Bodhisattva Avalokiteśvara and Mahāsthāmaprāpta are everywhere identical to those of sentient beings; merely by contemplating the marks of their heads, one knows this is Avalokiteśvara and knows this is Mahāsthāmaprāpta.’" "Bodies identical to sentient beings" refers to the disciples of that realm; while the forms of the middle and lower grades are completely different, the great bodhisattvas could be mistaken for one another. The sūtra says: "The sentient beings who are born there are all avaivartikas; among them are many who will attain buddhahood in one more birth, their number being extremely large," and so forth. Merely by contemplating the marks on the head can one distinguish the two sages: Avalokiteśvara's crown has a standing Buddha, while Mahāsthāmaprāpta's uṣṇīṣa has a jeweled vase. Second, explaining their attendance to show the necessity of contemplation.