It means that Karateka should never attack first. The usage of the “skill of martial arts” (BUGI) without good reason, as the basic concept of the arts (BUDO) is peace. It is the most unfortunate thing for human beings to be forced to use them.
Therefore “BUDO” exists to prevend from troubles or even wars. Thus it is the most detestable Thing to attack first (SENTE) at random.
Using “BUGI” as means to solve the trouble is the worst possible way. “BUGI” must only be used reluctanly when there is no other way to stop violence. Once they are used the peace must resume without failure. To do so one has to win decidedly.
Therefore there is a teaching in “BUDO” that one has to win by letting an opponent cut one`s skin but cut his(her) flesh, letting him (her) cut ones`s flesh but cut his(her) bones and let him(her) cut one`s bones but cut his(her) marrow. In the other words one has to defeat an opponent by all other means despite that one has the fatal wound.
Japanese “BUDO” is positive and has the broader viewpoint. “BUDO” was created for the purpose of self defence, which is the defence for winning.
And “BUGI” is used as the art of self defence by chance. It is very unfortunate to use “BUGI” for self protection. To avoid this misfortune, one is reminded to have “correct attitude” or hold oneself in readiness. Although there is an occasion to attack first that is only the strategial means to prevent any troubles without causing any more misfortunes.