The 4 Parajikas (Defeats) for a Monk

General Buddhism | 佛法研讨
1

Master Ri-Chang mentioned this:

那么“别解脱”就是比丘戒，比丘戒的重戒只有四条，犯了这个四条重戒的话那一定堕落，最严重、最可怕的罪！
BW Monastery 吉祥宝聚寺 — 第102卷B面

Curious, I googled for an answer:
The four parajikas (defeats) are rules entailing expulsion from the monastic Order (Sangha) for life. If a monk or nun breaks any one of the rules he/she is automatically ‘defeated’ in the holy life and falls from monkhood immediately. He is not allowed to become a monk again in his/her lifetime. Intention is necessary in all these four cases to constitute an offence. The four parajikas for bhikkus are:

  1. Sexual intercourse, that is, any voluntary sexual interaction between a bhikkhu or bhikkhuni and a living being.

  2. Stealing, that is, the robbery of anything worth more than 1/24 troy ounce of gold (as determined by local law).

  3. Intentionally bringing about the death of a human being, even if it is still an embryo — whether by killing the person, arranging for an assassin to kill the person, inciting the person to die, or describing the advantages of death.

  4. Deliberately lying to another person that one has attained a superior spiritual state, such as claiming to be an Arahant when one knows one is not, or claiming to have attained one of the jhanas when one knows one hasn’t.

Reference:
https://dhammawiki.com/index.php/4_parajikas_(defeats)

2

My searches led me to this article:

Did you know:

The 253 vows of a fully ordained monk–these are the ones explicitly prescribed for the ordained persons by the Buddha himself in the vinaya scriptures–in the Mulasarvastivadin school of vinaya are broadly divided into five categories or classes with sets of ten, twenty and so forth as you can see below:

That is the testament of the willpower and strength involved in being a member of the Sangha.

For that matter, I am aware that a Bhikkhuni will take on more vows:

Full Nun’s Vows (bhikṣuni, gelongma) — 364 vows
reference: Pratimokṣa - Wikipedia