"one is never too old to learn",which is a doctrine for us t

等同原则
双语对照
例句:
The doctrine of equivalents is an important principle in judging patent infringement.
“等同原则”是专利侵权判定的一项重要原则.

1、the doctrine of popular democracy,which practiced in Greece in the fourth century B.C.,（had spread） to the far reaches of the earth of the earth (in) the mid-twentieth century.
（见括号部分）
a) 去掉had:spread to the far reaches of the earth of the earth (in) the mid-twentieth century.变过去完成时为一般过去时,因为是在（in the mid-twentieth century）20世纪中叶做的事,而非完成（by the mid-twentieth century) 的事
b) 或者改 in 为 by :had spread to the far reaches of the earth of the earth (by) the mid-twentieth century.表示20世纪中叶已完成了在世界各地的传播
2、Moses,an Israelite leader and prophet,died just before the Israelites reached Palestine,（what） they believed was the "promise land" God had given them.
（见括号部分）what 改为 which == 引导非限定性定语从句（what不具备此功能）,在从句中做主语
3、The doctrine of popular democracy,（which practice） in Greece in the fourth century B.C.,had spread to the far （reached ）of the earth in the mid- twentieth century.
a) which was practiced (需要被动态==同第一题）；
b) 分词 reached 须改成名词 reaches == to spread to the far reaches of the earth 传播至地球的各个角落

应该是动名词
我是这样分析的：
I have discovered that （后接从句）：
【abandoning the doctrine of “juggling your life,” and making the alternative move into “downshifting”】（主语） brings （谓语）with it far greater rewards than financial success and social status.
翻译：
我发现,摒弃“经营生活”这种主义,选择另一种低速的生活,这样所获得的回报要远大于经济上的成功和社会地位.

非永久性原则
doctrine名词：原则 of impermanence形容词（非永久性的）作定语修饰doctrine
就好像这句：book of English(英语书）
应该好理解吧

先把长句化简
Because...,they relied on ... to justify sth. to be doing sth.
1. because从句已清楚；
2. rely on ... to do:
rely on 后面是复合宾语,即宾语（precedents）+不定式充当的宾语补足语（to justify their claim ）,意思是：依赖先例去证明他们的主张.
3. justify ... to be ...
语法结构同上,justify后同样是复合宾语,意思是：证明他们主张是法律；
4. to be merely declaring pre-existing law and not making up their own law是并列的两个不定式补足语,作their claim的补足语：
a）to be merely declaring pre-existing law 是仅只宣布着的先前的法律.
b）not (to be) making up their own law是没有修订着的他们自己的法律.
c）to be claring ... and not making是进行时态,即：正公布的...而不是正修订的...
结构清楚,翻译就简单多了：
因为国王的法官们缺乏英国法律的书面记录,他们就依赖先例[过去的判决]去证明他们的主张仅只是正宣布着的先前的法律而不是正修订着的他们自己的法律.

A theory we can't support for long time
three parts of the divide your soul