there is not one here 主谓部分
who has not in the course of the day had occasion to set in motion a complex train of reasoning,of the very same kind,though differing in degree定语从句,修饰one
其中有难词：
1.set sth in motion 开始做某事且不停地做
to start a process or series of events that will continue for some time
如 The Church voted to set in motion the process allowing women to be priests.
2.a complex train of
a train of sth 一系列
a series of events or actions that are related
如：The decision set off a train of events which led to his resignation.
本句中复杂结构：
1.of the very same kind
定语,修饰reasoning
2.though differing in degree
分词短语,修饰kind
翻译：可能没有这种人,他在一天内有时间对同样一类的（事物）进行复杂的理性思考,尽管这类的思考可能程度不同.
as that which a scientific man goes through in tracing the causes of natural phenomena.
as介词,（如同,像）,that which a scientific man goes through in tracing the causes of natural phenomena介词宾语
which a scientific man goes through in tracing the causes of natural phenomena 定语从句修饰that,
翻译：比如,一个搞科学的人（不可能）整天研究自然现象的成因.
这句话是举例说明上句,所以加上了“不可能”