arterial highway
To keep you going (that is, someone is helping you in the dark). Another example is given: the brilliance of pearls has never been dimmed by not seeing the sunshine at the bottom of the sea all the year round. The industry you are engaged in is different for you. Even if it is quite dangerous or risky in the eyes of others, it will still turn defeat into victory. As the saying goes, Renji has his own days! Congratulations to your friend!