It’s a good reason for postponing pleasures that you will then have more time in which you can enjoy looking forward to them. I remember exactly when… - Derek Parfit

Certain actual sleeping pills cause retrograde amnesia. It can be true that, if I take such a pill, I shall remain awake for an hour, but after my night’s sleep I shall have no memories of the second half of this hour. I have in fact taken such pills, and found out what the results are like. Suppose that I took such a pill nearly an hour ago. The person who wakes up in my bed tomorrow will not be psychologically continuous with me as I was half an hour ago. I am now on psychological branch-line, which will end soon when I fall asleep. During this half-hour, I am psychologically continuous with myself in the past. But I am not now psychologically continuous with myself in the future. I shall never later remember what I do or think or feel during this half-hour. This means that, in some respects, my relation to myself tomorrow is like a relation to another person. Suppose, for instance, that I have been worrying about some practical question. I now see the solution. Since it is clear what I should do, I form a firm intention. In the rest of my life, it would be enough to form this intention. But, when I am no this psychological branch-line, this is not enough. I shall not later remember what I have now decided, and I shall not wake up with the intention that I have now formed. I must therefore communicate with myself tomorrow as if I was communicating with someone else. I must write myself a letter, describing my decision, and my new intention. I must then place this letter where I am bound to notice it tomorrow. I do not in fact have any memories of making such a decision, and writing such a letter. But I did once find such a letter underneath my razor.

It has been widely believed that there are such deep disagreements between Kantians, Contractualists, and Consequentialists. That, I have argued, is not true. These people are climbing the same mountain on different sides.

What now matters most is how we respond to various risks to the survival of humanity. We are creating some of these risks, and we are discovering how we could respond to these and other risks. If we reduce these risks, and humanity survives the next few centuries, our descendants or successors could end these risks by spreading through this galaxy. Life can be wonderful as well as terrible, and we shall increasingly have the power to make life good. Since human history may be only just beginning, we can expect that future humans, or supra-humans, may achieve some great goods that we cannot now even imagine. In Nietzsche’s words, there has never been such a new dawn and clear horizon, and such an open sea. If we are the only rational beings in the Universe, as some recent evidence suggests, it matters even more whether we shall have descendants or successors during the billions of years in which that would be possible. Some of our successors might live lives and create worlds that, though failing to justify past suffering, would have given us all, including those who suffered most, reasons to be glad that the Universe exists.