question I am afraid that your discovery has already been heralded by the Buddha himself, although he does not call it a fourth sign or mark. The fourth mark is sometimes rendered as ashubha, or ugliness. The Buddha identified two modes of conditionality, one which is well known and is illustrated by the Wheel of Becoming, is the 12 nidanas moving from ignorance to old age and death. The other, which is not as well known but is in the Nidana Vagga of the Samyutta Nikaya, is positive and progressive. It moves from suffering through faith, delight, joy, calmness, bliss, concentration, knowledge and vision of things as they really are, disgust, dispassion, liberation, knowledge of the destruction of the biases. The importance of this dynamic sequence is that life can be made to flow towards better. However, life does not flow towards better automatically. It has to be cultivated and worked for, which is why we have to practice the four right efforts.
answer Each school will naturally interpret in its own way the many, often conflicting sayings attributed to the Buddha in the scriptures. It would however be going too far to maintain that the Buddha ever implied that ugliness was the Fourth Mark or Sign of Being. The “disgust for things as they are” of sutta 23 of the Nidana Vagga should be understood strictly within the very limited context of one’s own personal life. And our position is that not humanity, mankind, human beings, the human manifestation of life, let alone one’s own personal life, is the measure of things in space and time, but the overall all-embracing flow of existence itself, which, quite oblivious to our exertions or, for that matter, our disgust, goes on and on in its own one right direction. We take it for granted, as explained, that there is nothing wrong with existence and that the objective of the Buddha’s Middle Way devoid of extremes was and is the abandonment of all fixed views and to reconnect and reconcile us with its true nature as it is beyond our commonly limited and biased personal experience of it.
question I wonder what your support for this interpretation of humans experiencing Nature as progress might be. There’s abundant evidence in media of various sorts — good, bad, or indifferent in quality — of people who contrarily do not experience the overall course of Nature as progressive at all, but instead as destructive and teleologically negative, especially today in conditions of global warming, cyclones, tornados, earthquakes, oceans rising, meteorites, and so on.
answer If you look closely, all those unpleasantnesses you mention do not pertain to overall existence at all but are the result of mistaken views, immorality and mismanagement. When we say how man experiences the course of Nature we of course mean man unencumbered by these contingent shortcomings and mistakes that impair his vision, understanding and accomplishments – the reference standard is overall existence and not failing mankind.