When investigating History, it is important to recognize elements of the understanding of historical president.

We are given some of the tools in literature classes when we are told to investigate topics: use multiple reputable sources, try to find differing opinions on the specifics to find a more well rounded approximation to the nuances in a given topic, site your sources to give credit to the experts, but also to give your readers sources to go and find out for themselves if your take on a subject is valid or not.

CONTEXT OF AUTHORSHIP

How this applies to the field of history is similar. the difficulty is that for much of the time that people have been writing, they have been writing about the past and with different perspectives, which are based on their personal and cultural assumptions. It is striking reading Edward Gibbon’s Decline and Fall and then Reading Mary Beard’s take on the History of Rome. Gibbon has a severe distrust of religious institutions, and Beard has a fascination with the perspective of common people. Knowing the periods in which both are writing is important to understand the types of glasses that either are likely to wear so that in studying both we can come to a more well rounded perspective not only on Roman civilization but also on the history of the field as well. Gibbon, for instance, is considered one of the founders of the study of Rome he was a British politician during the American War for independence. His perspectives have been largely overridden by new and better forms of scholarship though by having a reputation of being a first, anachronistic or otherwise, it is still difficult to speak about Rome with out eventually talking about Gibbon. This can also be seen in Beard’s work, who is a contemporary Roman historian whose works are written in the 21st century, examining minute details in an attempt to bring the lives of common Roman women and men to life.

Clearly, if you take modern assumptions and compare them, you get a different perspective from the late 18th century. Reading enough of each of these authors also gives you an idea about the assumptions of the people writing, as contemporary historians can vary on details of the historical events in flavor almost as much as the the general perspectives between cultures and times.

CONTEXT OF PERIOD MINDSETS

Adjacent to these considerations is the context of the time that is being studied. It is not at all apparent that the cultural assumptions of one people group will be the same as that of another, and the same is true temporally as they are geographically. The introduction of ideas through philosophy, religion, and science that happen historically do happen in time, so one should not expect the same ideas in time A when they were not postulated until time B. However, it is important to note that there are some exceptions to this. One example is when an idea is brought up and not popularized or well executed, such as Romans inventing a steam-powered spinning device. Since these devices were not well executed, and not popularized and lacked the material strength necessary to generate the power that the steam engines of the industrial revolution needed to create to power factories and locomotives, they were largely forgotten, and did not significantly contribute to the ideas of the eras that they inhabited. Conversely, it would be incorrect to say that Darwin was the first person to posit the power of “slow change over time” or that “only the strong survive.” These ideas had been floating around in the social and scientific circles of Western Europe before he managed to apply them to biology. The popularization of such ideas into cultural influences is not present to all people at all times. This can be seen in the literature of different eras and how they portray what is good. To the ancients, it is not at all obvious that there is a moral value that is common to all people, though some philosophies and religious ideas on that topic did evolve over time. To the early writing civilizations, humans were often seen as mistakes or as slaves to the gods. In other civilizations, only the king or priesthood of a region would be considered of any value in a cosmic sense, variously as god’s avatar or representative on earth. 

QUALITY OF INFORMATION AVAILABLE
Additionally, it should not be assumed that the same methods we use in contemporary civilization would have been used to record events. Often in Mesopotamia, the practice was to exaggerate the numbers in battle that were won by kings and the level to which they crushed their enemies. Reading some of these texts might imply that a Persian or Assyrian king had completely erased a civilization from existence yet the following year the same king will be back fighting the same civilization, so clearly this early form of recording is not meant to record the exact picture of what happened but more a propaganda of the king who commissioned the source. The desire of writers to at least attempt to be vigorous with there material is a development that might be traced to Herodotus if you are feeling generous, though modern methods of historical analysis really have been developed over the last four hundred years and only approached the rigor that most of us might feel comfortable with in the last century. Further distortions might be found in an author’s desire to sensationalize the material for wider reading. A clash between two city states each with a thousand soldiers may have been impressive to your everyday farmer, but if you have the King of Kings drain an entire continent of men, creating an army numbering in the hundreds of thousands, marching on the good people of Greece, that is an epic story that still finds appeal two and a half millennia later. This is before one needs to consider how much information and the quality of the information that a historian has. One then should also consider the why or if it is that some information is exaggerated, downplayed, or omitted.

IGNORANCE IS NOT STUPIDITY
However, it is important to remember that though previous generations down the eons may not have had our knowledge they are no less intelligent, wise or capable as we are today. We should not be so cynical as to entirely dismiss the abilities of these civilizations, despite their lack of more rigorous scientific methods. Most people are not so rigorous in their own assumptions about the world that would approximate what we are best capable of saying about being human in this century in our own context, and are able to live productive and meaningful lives. Here are a few examples.

The medicinal practices of the ancient would, though crude by modern standards, were not entirely without merit. Thousands of years of testing and tribal knowledge were able to produce some surprising results. The Old Babylonians (1800-1600 CE) through trial and error were able to build tables of Pythagorean triplets many centuries before Pythagoras or Euclid were even born. The Ancient Greeks were able to approximate the circumference of the earth and even the idea of atoms and some rudimentary understanding of material properties due to the shape of these atomic structures. In architecture, the balance of arches was also determined without the current understanding of physics, just by the ratio of thickness of support structures to the span of the arch. Roughly, the formula was that a supporting column was 20 to 25 percent of the span of its arch. This ratio seems to have been something that was known since the construction of the Stone Age Göbekli Tepe and continued in some capacity through the Bronze, and Iron ages.  These discoveries were often facilitated by experimentation of specialists patronized by the wealthy citizens of a civilization. One example of this methodical evolution can be observed in the bent and step pyramids of Egypt. The building and experimentation of the step pyramid led to a more ambitious project started in the bent pyramid. However, the steeper angle of the bent pyramid was not able to support the weight of the stones that were being laid down so the slope was changed halfway through for the sake of stability. The final geometric form of the Great Pyramids was the culmination of this generational experiment. 

Thus, through what today seems like vast amounts of time, humans have historically been able to find clever solutions to challenges by trial and error. Successful principles that worked within a framework would be passed down, and unsuccessful ones often died out. Thus, these practical principles were passed down to future generations through teachings, traditions, and writing. These rules of thumb developed in ancient times facilitated many of the architectural wonders of the ancient and medieval world. When civilizations collapsed, this information could be lost, but the nature of the physics is not something that changes. The principle of guided observation, building off existing principles, and “if it ain’t broke don’t fix it” can, in the right hands, yield impressive results without modern scientific methods. It is merely the presence of the funding necessary to rediscover the lost principles, if any, that hinder the recovery of this information.

In short, if an author from the past says something, there are a few considerations that are needed to find out what they were really trying to say.

1. What is the genre

2. What is their motive

3. What is the historical contextual

4. What is their understanding of the subject?

     A. Does it differ from their contemporaries?

     B. From ours? If so, how did they get to their understanding?

For the benefit of the reader I will say that my own level of understanding of the subject matter is of a chronically curious, and dedicated but non-academic student of history. I have read many secondary sources from leading experts including: lectures and surveys on various histories and biographies ranging from ancient Sumer to the beginning of the twentieth century. This amounts to thousands of hours of content and research over the last decade. This does not place me in the ten thousand hour expert level, so I encourage my readers/ listeners to continue to learn about the connected subject matter to learn more details.

FURTHER READING
If you are curious about some of these specifics some additional resources that flesh these ideas out in more detail, to whom I am indebted:
Lectures
The Great Courses:
Ancient Mesopotamia: Life in the Cradle of Civilization ~ Dr. Amanda H. Pomona
History of Science Before 1700, The ~ Dr. Lawrence M Principe
Books
Decline and Fall of the Roman Empire, The ~ Edward Gibbon
Rise and Fall of Ancient Egypt, The ~ Dr. Toby Wilkinson
SPQR ~ Dr. Mary Beard
Things We Make, The ~ Dr. Bill Hammack
Podcasts
History of Byzantium Podcast, The (Specifically the non-narrative episodes about existing sources for any particular century) ~ Robin Pierson
History of Rome Podcast, The (A good consumable overview) ~ Mike Duncan