这里那么多的that which 表示什么，第一个which表示little that吗

it is human, perhaps ,to appreciate little that which we have and to long for that which we have not but it is a great pity that in the world of light the gift of sight of used only as a mere convenience.

it is human, perhaps ,to appreciate little that 【which we have】 and to long for that 【which we have not】 but it is a great pity【 that in the world of light the gift of sight of used only as a mere convenience】。

个人理解：

that和 with肯定不是连在一起表示什么！

第一个little that是连在一起的，具有名词的性质，你可以理解为‘那么的少’，后面的which we have为which引导的定语从句修饰前面的 that。

第二个明显是借此for后面的宾语，也具有名词性质，后面which引导的从句which we have not，同样为定语从句。

后面的你应该很好理解，为形式主语it引导的复合句，后面的从句为真正的的主语。但是我想说最后面的那一句应该有点错误，请看红色部分，语法上根本不成立。请查看原句！