This unit covers the removal of Native American
tribes to Indian Territory. Today, we judge the
methods used by the US government harshly,
believing that the forced relocation of these tribes
was wrong. Some historians believe that using
present-day ideas about right and wrong to judge
the past makes it more difficult to understand
history. This idea is known as presentism.
What do you think? Do you agree that the values
of today can't be compared with the values from
another era? Or do you think that what is right and
wrong today still applies to the actions of people
in history?

The investiture controversy began as a power struggle between pope gregory vii (1072–85) and henry iv, holy roman emperor (1056–1106).[2] a brief but significant struggle over investiture also occurred between henry i of england and pope paschal ii in the years 1103 to 1107, and the issue played a minor role in the struggles between church and state in france, as well.by undercutting the imperial power established by the salian emperors, the controversy led to nearly 50 years of civil war in germany, and the triumph of the great dukes and abbots. imperial power was finally re-established under the hohenstaufen dynasty. historian norman cantor:

The study of where things are 

It is nonrenuable which means that once you have used it, it's gone forever.