Many insights into the practical aspects of living, both religious and secular, are to be drawn from the numerous stories in the Mahabharata involving human beings (from all walks of life) and celestials. One emerging truth is that all are governed by the law of Karma that enjoins each individual to be responsible for his deeds, both good and bad, said Nagai Sri Mukundan in a lecture.
King Santanu of Hastinapura was destined to have a brief married life with Ganga due to Lord Brahma's curse, because in his earlier birth, when once in the assembly of celestials at the Brahma Loka, he had glanced longingly at Ganga seated next to Brahma and Ganga too reciprocated.
In another context, the Ashta Vasus were subject to Vasishta's curse for stealing the sacred cow Kamadhenu from his hermitage. In response to the pleas of the repentant Vasus to exonerate them from human birth, the sage gave a one-year term of human life for the seven Vasus who had been accomplices to the theft and a full life-term for the one Vasu who had actually stolen the cow. The Vasus, who knew about Brahma's curse to Ganga, approached her to help them in this curse and she agreed.
So, when Santanu wished to marry Ganga, she laid a condition that he should not question her acts and that if he did so she would leave him. Ganga drowned seven sons that were born to them.
Unable to bear the loss of the seven sons, Santanu questioned Ganga's act at the birth of the eighth child. She then said she would have to leave him and that this son named Devavrata (who later became Bhishma) would be brought to him after 16 years. Devavrata became an accomplished youth who had the guidance of eminent preceptors — scriptural knowledge from Vasishta and archery from Parashurama. Santanu's wish to marry Satyavati was made possible only at the expense of Devavrata's future because the kingdom had to be given to Satyavati's sons.
Not only the heir-apparent Devavrata had to renounce his right to the throne but also had to vow a lifetime of celibacy that won for him the name Bhishma.