Why is the word "perspective" important to historians?
Perspectives are important for all historians, because there is no such thing as objective history. This means that all historians have different ways to interpret events in the past. In other words, all events are known and told from the the biases of historians. We call his historiography. It is also important to add that all historians look at history with different interests in mind. Some historians examine intellectual history; others examine social history; still others look at another aspect of history. All of these are perspectives.
An example might be helpful.
When we come to the poems of Homer, some historians believe that the poems accurately reflect the Bronze Age. Other historians say that Homer's poems are completely made up and have no bearing on the Bronze Age. Most historians fall somewhere in the middle. The various views here are all perspectives on the same poem. This shows that differences of opinion exist. History, in this sense, is all about perspectives.