And what are the Four Seals of Dharma as mentioned by Dondrup?
They are referring to these four characteristics or truths of universal existence :
1. that everything in this world is
impermanent;
2. that everything in this world will bring us
suffering (unsatisfactory);
3. that everything and every phenomena in this world is
absent of 'self' or permanent body;
4. that
only Nirvana can bring us ever lasting peace and happiness.
"The Three marks of existence, within Buddhism, are three characteristics (Pali: tilakkha?a; Sanskrit: trilak?a?a) shared by all sentient beings, namely: impermanence (anicca); suffering or unsatisfactoriness (dukkha); non-self (anatt?).
According to Buddhist tradition, a full understanding of these three can bring an end to suffering (dukkha nirodha, ??). The Buddha taught that all beings conditioned by causes (sa?kh?ra) are impermanent (anicca) and suffering (dukkh?) while he said not-self (anatt?) characterises all dhammas meaning there is no "I" or "mine" in the conditioned as well as the unconditioned (i.e. Nibb?na).[1][2] The central figure of Buddhism, Siddhartha is believed to have achieved Nirvana and awakening after much meditation, thus becoming the Buddha Shakyamuni. With the faculty of wisdom the Buddha directly perceived that all sentient beings (everything in the phenomenology of psychology) is marked by these three characteristics:
Anicca (Sanskrit anitya) "inconstancy" or "impermanence". This refers to the fact that all conditioned things (sankhara) are in a constant state of flux. In reality there is no thing that ultimately ceases to exist; only the appearance of a thing ceases as it changes from one form to another. Imagine a leaf that falls to the ground and decomposes. While the appearance and relative existence of the leaf ceases, the components that formed the leaf become particulate material that may go on to form new plants. Buddhism teaches a middle way, avoiding the extreme views of eternalism and nihilism.[3]
Dukkha (Sanskrit duhkha) or dissatisfaction (or "dis-ease"; also often translated "suffering", though this is somewhat misleading). Nothing found in the physical world or even the psychological realm can bring lasting deep satisfaction.
Anatta (Sanskrit anatman) or "non-Self" is used in the suttas both as a noun and as a predicative adjective to denote that phenomena are not, or are without, a self; to describe any and all composite, con-substantial, phenomenal and temporal things, from the macrocosmic to microcosmic, be it matter pertaining to the physical body or the cosmos at large, as well as any and all mental machinations, which are impermanent.
There is often a fourth Dharma Seal mentioned:
Nirvana is peace. Nirvana is the "other shore" from samsara."
http://en.wikipedia.org/wiki/Three_marks_of_existence