At this time, in the midst of the fearful, limitless ocean of cyclic existence, which has no end or boundary, we possess the precious ship of the freedoms and favors that know about and establish such benefit and goodness. Control of it has been taken by a steersman who is our spiritual friend:
If we do not cross the limitless ocean of samsara
Now at the time of having attained this precious ship,
How can we ever do it at another time
When painful waves of the kleshas are always utterly raging?
If we have a great ship which will serve our purpose, we should use it to cross the watery ocean. Similarly, having attained this ship of humanity, we should cross the great beginningless, endless ocean of samsara, so fearful and unbearable. Because we are wandering in a realm of constant birth, old age, sickness, and death, samsaric situations are never bearable.
Shantideva says in the Bodhicaryavatara:
Whoever with the support of this ship of human birth,
Can cross the great waters of the river of suffering,
Since later such a ship may be difficult to find,
Would be wrong to sleep at this time, because of stupidity.