Up to the age of twelve years, Ja’afar (AS) was brought up under the guidance of his grand father Imam Zainul Abedeen whose main concern was to worship his maker and reflect on the tragic events of Kerbala and whose main avenue of teaching was through supplications.
Twenty two years had lapsed since then, yet the remembrance of the tragedy of Kerbala was still fresh in his memory. So, as soon as Imam Ja’afar (AS) gained understanding, he was profoundly impressed by the continuous grief of his grandfather, so much so that he felt as if he himself was present during that tragedy. He also contemplated on the presence of his father Imam Baqir (AS), who was only three years old, at that tragic time. Imam Sadiq(AS) considered it his duty to convene the recitation gatherings (Majalis) about the sorrowful event of Kerbala.
He was twelve year old when his grandfather expired. Then up to the age of 31 he passed his time under the guidance of his father Imam Baqir(AS). It was the time when Ummayad politics was tottering and muslims were approaching Imam Baqir(AS) in thousands. Their need for knowledge was fulfilled by the Imams of the Ahlulbayt.
In 114 Hijri(732 AD) Imam Baqir (AS) died, and the responsibilities of Imamat devolved on the shoulders of Imam Ja’afar Sadiq. Hisham Ibn Abdul Malik was still ruling in Damascus and political disturbances were afoot. The passion of taking revenge on Bani Ummaya was strong and several descendants of Imam Ali(AS) were preparing themselves to overthrow the regime. Most prominent among them was Zaid, the respected son of Imam Zainul Abedeen (AS) His religious zeal and piety were known throughout Arabia. He was Hafiz of the Qora'an and he had taken upon himself the stand of removing the tyranny of the Ummayads.
This was a very precarious juncture for Imam Sadiq(AS) As regards the tyranny of the Ummayads, he agreed with his uncle Zaid for whom he had a great deal of respect. But his far sighted judgement as Imam could clearly see that Zaid’s rising against the well organized Ummayad forces will be of no avail. He therefore advised him not to start this venture. But Zaid was too far out in his zeal and he would not stop. Many thousands of Iraqis had sworn their allegiance to Zaid and he was quite optimistic about his success. He took his forces to Kufa, gave a great battle but was killed in the end. The Ummayads were as brutal as ever. They hung the body of Zaid on the gates of the city of Kufa which remained their as a reminder for several years. One year after Zaid’s death, his son Yahya gained the same path and received the same fate. Imam Sadiq(AS) was aware of all this but realized that this was not the time to take any such active part. His main occupation was to spread the religious sciences of Ahlulbayt as much as possible while time was on their side.
source : http://www.al-islam.org