4 Divine messengers.
Seeing the 4 divine messengers shook the Buddha to his core and this led him to seek salvation. The 4 divine messengers are old age, sickness, and death, and the 4th sight was an ascetic homeless seeker after truth. Thus he knew what he had to do. Life as he knew it had no more attraction for him since it would all vanish now or at the time of death.
An eternal solution to the problem of life and death needed to be found. It took the Buddha nearly 6 years of intense struggle to discover the light which shines continuously, the Dhamma, The Truth, law. Justice.
We are so fortunate to have access to this teaching which we call the Marvel. It truly transforms us. Let us dedicate our entire energy to this single aim of salvation at any cost.