Indrajala wrote:Earlier a Tibetan monk said to me, "Why bother studying Sanskrit? Everything is available in Tibetan."
Actually, some texts are only available in Chinese, such as Asaṅga's commentary on Nāgārjuna's Mulāmadhyamakakārikā
The importance of learning Sanskrit is that when reading the texts in the words that the author actually wrote, you can gain an accuracy and depth of understanding not available when reading in translation (Tibetan or English). For example, sometimes the key ideas of passages require an understanding of Sanskrit grammar, a play not just on words but on grammar, which are often lost in translation.
Like Ratna said, knowledge of Sanskrit helps clarify Tibetan ambiguities and I think that if you want to translate something that was originally written in Sanskrit it is imperative to know Sanskrit well. I think even in cases where there is no Sanskrit original it is still important to know Sanskrit so that when you reference the Mahāvyutpatti
you have a better understanding of what the Tibetan is attempting to render.
One thing to keep in mind is that in order to take advantage of Sanskrit beyond dictionary Sanskrit, you are going to need to invest four years of study. It is certainly worth it, but if you have limited time Tibetan may give you more bang for your buck. It is much easier to learn (you can get up and going in a year or two) and it also gives you access to a much larger cannon of Buddhist texts.