Several years ago, a friend of mine, who is more than ten years senior to me and was a student philosopher at that time, told me about two online shopping sites which he said were indispensable if I was to be a researcher of humanities: 日本の古本屋 and AbeBooks.
He said something like this: When doing research in humanities, the time will surely come when I will need old and used books. It is probable that some of them were published a century ago. To deal with this necessity, the two sites are of real service. So I should remember them.
The sight of him tackling an old book, which seemed to have come unbound long before, with pages worn and stained all over, was convincing.
It has been a long time since that day, but the time finally came. I need some books which are out of print and I cannot find on Amazon. And what he said was true. I found them available on AbeBooks. However, I don't know for now how to get them. Maybe a credit card is needed, which I refrain from making. It seems that I am finally on a long hard road toward a true philosopher.