IMPORTANT DAYS IN THE BUDDHIST CALENDAR: MANJUSRI
Other than Vesak Day, another significant day that usually falls in May is the festive day of MANJUSRI. This is celebrated on the 4th day of the 4th month of the lunar calendar.
The Rider Encyclopedia of Eastern Philosophy and Religion, edited by Stephan Schumacher and Gert Woerner, Rider, 1986, gives the following entry:
Manjushri. Sanskrit (Japanese Monju), lit. `He Who Is Noble and Gentle'; the bodhisattva of wisdom, one of the most important figures of the Buddhist pantheon. He first appears in the Arya-manjushri-mulakalpa, a work dating from before the 4th century. Usually Manjushri is iconographically depicted with two lotus blossoms at the level of his head, on which his attributes - a sword and a book of the prajna-paramita literature - are placed. These attributes stand for the wisdom embodied by Manjushri, which dispels the darkness of ignorance.
From An Introduction to Buddhism by Peter Harvey, Cambridge University Press, 1990:
Another important Great Being is Manjusri `Sweet Glory', who with Samantabhadra, `The All-round Blissful One', is said to be the helper of the heavenly Buddha Sakyamuni. A tenth stage Bodhisattva, he is seen as the greatest embodiment of wisdom, and has the special task of destroying ignorance and awakening spiritual knowledge. Accordingly, he is shown holding a lotus on which rests a copy of a Perfection of Wisdom Sutra, and wielding a flaming sword, symbolic of the wisdom with which he cuts away delusion. He is seen as the patron of scholars and a protector of Dharma-preachers. Those who devoutly recite his name, and meditate on his teachings and images, are said to be protected by him, to have many good rebirths, and to see him in dreams and meditative visions, in which he inspires and teaches them.
From Popular Deities of Chinese Buddhism by Kuan Ming, Kuan Yin Contemplative Order, Sincere Hampers and Floweray Pte Ltd, 1985:
Wen-Shu-Shih-Li P'usa (Manjusri Bodhisattva)
...According to Chinese Buddhism, he was informed by Sakyamuni Buddha that it was his duty and responsibility to seek the instruction and salvation of the Chinese people by making his abode at the Wu-tai Shan in the Shansi province, and there to cause the Wheel of Dharma to turn incessantly.
Manjusri's popularity in the northern Buddhist countries stretches from Nepal, Sikkim, Tibet, China, Mongolia, Korea to Japan. Millions of Chinese Buddhists daily recite "Namo Wen-shu-Shih-Li P'usa" to seek his blessings. He is the most popular Bodhisattva among the Buddhists of Tibet and Nepal where even young children constantly repeat his mantra, `Om-ara-pa-chana-dhih' which is a prayer for developing wisdom. Holy books compiled by lamas often begin with the mantra `Namo Guru Manjugoshaya' as a mark of respect to Manjusri for he is indeed the `lamp of wisdom and supernatural power' who is the destroyer of falsehood and ignorance from the minds of all beings.
...Temples dedicated to Wen-shu P'usa are a rarity but a statue honouring this Bodhisattva can be found in most Chinese temples. Generally Wen-shu either appears in a triad with the Buddha Sakyamuni and Pu H'sien P'usa or, with Kuan Sih Yin P'usa and Pu H'sien P'usa, as shown in the Pantheon of Deities.
Note: Pu H'sien P'usa is known in Sanskrit as Samantabhadra Bodhisattva, and Kuan Sih Yin P'usa as Avalokitesvara Bodhisattva.