The Three Obstacles and Four Devils

What struck me for this Gosho is the following quote:

"Something uncommon also occurs when an ordinary person attains Buddhahood. At such a time, the three obstacles and four devils will invariably appear, and the wise will rejoice while the foolish will retreat. "

I believed you all have heard this phase millions over times.. However, have you guys wondered what was the background and from which Gosho? Indeed, this phase was from the Gosho, <<The Three Obstacles and Four Devils>>.

Background
It was a letter to Hyoe no Sakan Munenaga, the younger of the two Ikegami brothers. Munenaka is Munenaga's elder brother and had earlier been disowned by their father, Yasumitsu for taking on faith. This letter was a guidance for Munenaga to decide if he should trade his beliefs for the rights of inheritance of his father. Both brothers actually based on the Daishonin's guidance managed to upheld their faith and eventually after 22 years of united practice, led their father to accept the Daishonin's teachings.

My thoughts: Firstly, what are the 3 obstacles and 4 devils? How is this shown and highlighted in this Gosho since it was titled such? For the details, I guess, you guys got to read it up yourself but the 3 obstacles are namely,
(1) the obstacle of earthly desires, or obstacles arising from the three poisons of greed, anger, and foolishness 烦恼障
- arises based from our "fogged" vision of the world. This fog is caused by the 3 poison.. Something that is based on our surroundings
(2) the obstacle of karma, obstacles due to bad karma created by committing any of the five cardinal sins or ten evil acts 业障
- arises mainly from those whom we are responsible for.. like our loved ones, sons/daugthers or juniors
(3) the obstacle of retribution, obstacles caused by the negative karmic effects of actions in the three evil paths 报障
- arises mainly from those whom we are have to report to.. like our superiors, fathers, mothers, elders etc
The 4 devils here refers to are namely,
(1) the hindrance of the five components, obstructions caused by one's physical and mental functions
- this refers to our physical self and is commonly know as sickness, illness etc 阴魔
(2) the hindrance of earthly desires, obstructions arising from the three poisons
- this refers to mainly our troubles, concerns, desires etc 烦恼魔
(3) the hindrance of death, meaning one's own untimely death obstructing one's practice of Buddhism, or the premature death of another practitioner causing one to doubt 死魔
- this is the result of death
(4) the hindrance of the devil king, who is said to assume various forms or take possession of others in order to cause one to discard one's Buddhist practice 天子魔
- this is commonly noted when people are trapped in the state of rapture

In this Gosho, the Daishonin was quoting from a number of incidents that was related to slandering the Law and that all had came to a bad end. Mainly because they were not true to their faith and were easily shaken/tempted when the 3 obstacles and 4 devils presented themselves. Here the Daishonin could be said to be using these as examples for Munenaga to be able to appreciate and that he should not simply base his life on the desire to inherit his father's fortune. As it is highlighted by the Daishonin that one leads on to another until one who does not realises the occurrences of the 3 obstacles and 4 devils, met with his/her death or misfortune. The Daishonin is strict because the Law is strict. Thus laying down the ground works for us to identify the 3 obstacles and 4 devils more easily and therefore not to be defeated by them.

In addition, it is highlighted strongly that even if someone who is in superior to you or who is of higher religious status, do not follow them blindly but correct them if they are indeed erroneous. This was seen in the form of Yasumitsu, the Ikegami brothers' father and Priest Two Fires. Therefore I would like to urge all of you to build a strong foundation of your faith so as not to be shaken or tempted that easily. Allow me to then end this sharing with the strict words of the Daishonin,

"This time I am sure that you will give up your faith. If you do, I have not the slightest intention of reproaching you for it. Likewise, neither should you blame me, Nichiren, when you have fallen into hell. It is in no way my responsibility. It is an undeniable fact that fire can at once reduce even a thousand-year-old field of pampas grass to ashes, and that the merit one has formed over a hundred years can be destroyed with a single word."