Whether one is alive, or even after death, if one is not clear, one becomes a slave to oneself. One has difficulties escaping from the Six Paths of Samsara and from ignorance. One eventually loses oneself and ends up living a life full of suffering. That is why Shakyamuni Buddha says that we have to be clear and must not lose ourselves, so that we can live most happy and appreciative lives.
We can all do that. That is why Shakyamuni Buddha gave us 84,000 teachings and the precepts. In the five precepts, the last precept is to abstain from intoxicants, taken to induce heedlessness. The reason is that as long as one keeps this vow, one will not lose oneself. One will always be clear, so that one will not carry out ignorant actions and have regrets; thus one will not accumulate negative karma. At the same time, one will become a correct human being that does his or her correct duty and function as a human being should. One can then have a most joyous and appreciative life, life after life.
When one uses liquor, for example, for one’s health, or as a certain medicine for one’s body, if one does so in moderation, one will not lose oneself and will not be breaking the precepts.
But when one takes too much liquor and makes ignorant speech and action, which bothers others and brings suffering to oneself, that is breaking the precept. That is why Shakyamuni Buddha made this last precept, so that we do not go off the correct path.
Usually, when one drinks too much liquor, one loses the precious time of “moment-to-moment”. In that moment, if one does make a mistake, that mistake will last a long time; sometimes it can even last into one’s next life. One can ruin oneself.
Shakyamuni Buddha says that the person that keeps the precepts will never fall onto the wrong, evil path.