Mr. Frans,
Thank you for your question about the aspiration of Prince Vesantara for his great sacrfice for the sake of the happiness and welfare of other beings. Before answering to your question, first of all, let’s discuss what is meant by the word bodhisattva or bodhisatta.

The Pali word ‘Bodhisatta’ simply means a being who aspires for a ‘bodhi’ or ‘enlightenment’. In fact, the concept of bodhisattva (meaning Buddha-to-be) is one of the most important concepts in Buddhism, specially in Mahayana Buddhism. Etymologically the term can be seperated into two parts, namely ‘bodhi’ taken from the root ‘budh’ which means to be awake, awakening and enlightenment and ‘sattva’ derived from the root ‘as’ which means ‘to be’ that implies a being or one whose essence is enlightenment or a seeker after Elightennment. Whereas, the word ‘bodhisattva’ corresponds to the Pali word ‘bodhisatta’ which also means one who is attached to or desires to gain Elightenment. In original Pali Buddhism, the term bodhisatta is used more or less exclusively to designate Gotama Buddha prior to his Enlightenment. When Gotama Buddha appeared, he himself as well as others used the term bodhisatta to indicate his career from the time of his renunciation upto the time of his enlightenment. Later, its use was extended to denote the period from Gotama’s conception to the Enlightenment and, thereafter , to all the Buddhas from their conception to Buddhahood. By applying the doctrine of karma and of rebirth, which had general acceptance even in pre-Buddhist India, the use of the term was further extended to refer to the past lives not only Gotama, but also of those rare beings who aspire for Sammasambodhi or Perfect Enlightenment. The oldest tradition as contains in the Mahapadana Suttanta gives details of six Buddhas, prior to Gotama. This discourse is attributed to the Budha himself, who also gives the time, caste, family, length of life etc. of his predecessors. Later the Buddhavamsa of the Khuddaka Nikaya, enumerates the number becomes twenty-five.

In order to shorten our discussion, let’s come to your issue of Vessantara Jataka, in which you’ve raised a question whether an ordinary being could perform such great sacrifice as done by Price Vesantara. It is important to be noted here that Jataka stories relate the selfless nature of the bodhisatta in order heim attaining Buddhahood. Jataka stories represent the bodhisatta either as the hero practising one of ten paramitas, or minor character or even as a mere spectator. These ten paramitas are dana (charity), sila (morality), nekkhama (renunciation), pannya (wisdom), viriya (energetic effort), khanti (patient), sacca (truthfulness), adhitana (aspiring to be a Buddha), metta (loving kindness) and upekkha (equanimity).The earlier Sanskrit Buddhist text gives six paramitas and ten stages in the spiritual progress of the bodhisattva. In early Buddhism, a bodhisatta is limited to those rare beings who are specially gifted. A bodhisatta is called so, if he has made a vow to be a Buddha in front of a Buddha of his time. Take for instance in the case of Bodhisatta Sidharta, his career as a bodhisatta started from the time when he was born as an ascetic Sumedha and made a vow in front of Buddha Dipankara. Since then he had been practising the above ten paramitas. To make it clearer a bodhisatta’s career should start with his making a resolution before a Buddha which is called ‘abhiniharakarana or mulapranidhana to be a Buddha for the welfare and liberation for all creatures. In making abhinihara one has to follow first a step called manopranidhi when he resolves his mind to becomes a Buddha without declaring his intention to others (in Mahayanist it is called bodhicitta).

From the above explanation, we can get a clear picture that a bodhisattva is one who aspires to attain enlightenment and in order to fulfill his ideal, it is needed for him to practise ten paramis. In the case of Prince Vessantara, as mentioned in the Vesantara Jataka, he has clearly practised dana paramita by sacrificing his body for the sake of happiness and welfare of other beings. Really it is a great sacrifice that can be done only by a bodhisattva. In this regard, you may ask a question that prince Vessantara has commited suicide. Looking at from the worldly view, it is true that he has done so, but the most important is that he has done so for the sake of attaining Buddhahood and for the welfare of other beings. It is very different from the deeds done by an army who sacrifice his life in the battle. From early Buddhism we can get an idea that in order to be a bodhisattva there are many requirement that has to be followed (some of them see above). So you could see in our day to day life there are many people donate a part or some part of their bodies for the sake of others. Even few of them are ready to sacrifice their life for the sake of others. Of course, these deeds are very good, specially for the doers, and definitely will acquire a good kamma. But to justify whether they are bodhisattvas or nor is really a big problem, since we can not understand whether they have met the Buddha in their previous lifes, their motivation etc. Lastly, to answer your last question, whether such deed as done by Prince Vesantara could only be done by those who have attained liberation, you could think of yourself. From early Buddhism, the definition of a bodhisattva is one who aspires to attain Enlightenment or become a Buddha; so he hasn’t become a Buddha yet. those deeds are done in order to be a Buddha (fulfilement of his paramis). I hope you also can be a Buddha in future…

May you be well and happy!
Sukhi ca arogyo bhavatu’ti!