in which he possessed a very real dark side (though what this entails, we don't really know) and the ways in which he was deeply ashamed of it.

In addition, it's worth noting that from the very beginning, Jekyll's intentions behind the creation of Mr. Hyde were corrupt, given that part of his goal was actually to find a way in which he could have the opportunity to act out his own worst inclinations with immunity. This was the reason he ultimately was so drawn to the Hyde persona: because Jekyll (or, perhaps, that darker part of Jekyll himself) wanted to indulge in those actions while not suffering any ill effects as himself. Honestly, I think this is one of the most interesting and disturbing elements of Stevenson's story, and I would suggest you consider just what these details might suggest about Jekyll himself.

Robert Louis Stevenson's novella Dr. Jekyll and Mr. Hyde has been regarded by some as "one of the best guidebooks of the Victorian era" as its duality of Dr. Jekyll represented for some a basic dichotomy of the period, the "outward respectabiity and inward lust" in what was a hypocritical society.

• Behavior

Before his transformation, Dr. Jekyll is a cerebral and refined man. Interested in religion, literature, and especially science, Jekyll associates with other professionals and ladies. But, there is a more primal side to Dr. Jekyll that he finds difficult to surpress, so he tries to separate himself. So, in the other side of his house, a side where there once was a garden, Jekyll experiments in his laboratory. When he is able to separate himself, a man emerges that is called Mr. Hyde, described by those who see him as "deformed," and a "murderous mixture of timidity and boldness."  He kills Sir Danvers Crew, and tramples a young girl.

• Appearance

Dr. Jekyll has good manners and has  

...a large, well-made, smooth-faced man of fifty, with something of a slyish cast perhaps, but every mark of capacity and kindness—you could see by his looks that he cherished for Mr. Utterson a sincere and warm affection.

But, Hyde is pale and dwarfish, "a murderous mixture of timidity and boldness." Strangely, people have difficulty in describing Hyde, but they say that there is something evil about him and they compare him to a monkey or an ape in appearance. Utterson says there is something "troglodytic" about Hyde. Further, he describes Hyde as a "murderous mixture of timidity and boldness."

• Relationships to others

Jekyll becomes estranged from others when his darker side begins to overtake him. His relationships with gentlemen such as Mr. Utterson, Dr. Lanyon, and Mr. Enfield are certainly damaged. When Dr. Lanyon witnesses the transformation of Jekyll into Hyde in Chapter 9, he is profoundly altered as he watches him put a cup to his lips and

A cry followed; he reeled, staggered, clutched at the table, and held on, staring with injected eyes, gasping with open mouth; and as I looked ....the features seemed to melt and alter—and the next moment I had sprung to my feet and leaped back against the wall, my arm raised to shield me from that prodigy, my mind submerged in terror.

Dr. Jekyll's darker side takes over and his refined friends are abandoned. He is now not only deformed in body, but in soul. 

In the concluding chapter of The Strange Case of Dr. Jekyll and Mr. Hyde, Jekyll notes that all men have a dualist quality to their nature. Through his scientific knowledge, Jeckyll was able to separate the one from the other. From this experiment emerges Hyde, who is a physical manifestation of the worst impulses and inclinations long suppressed by Jeckyll, made free and unrestrained.

Jeckyll notes, in that same chapter, that Hyde's appearance or presence invariably causes among other people a great deal of repugnance. This is because Hyde is a walking incarnation of a human being's own worst nature. The reaction is, by all accounts, universal.

We see this reflected within the plot of the story. Everyone who meets with Hyde or has an encounter with him exhibits a visceral distaste for him, which often they themselves do not fully understand. We see this in the story's opening chapter, when Enfield tells the story of his encounter with Hyde, noting that "I had taken a loathing to my gentleman at first sight. So had the child's family, which was only natural." (ch. 1).

Later, Utterson also describes a similar reaction upon his own first encounter with Hyde:

Mr. Hyde was pale and dwarfish, he gave an impression of deformity without any nameable malformation, he had a displeasing smile, he had borne himself to the lawyer with a sort of murderous mixture of timidity and boldness, and he spoke with a husky, whispering and somewhat broken voice . . . but not all of these together could explain the hitherto unknown disgust, loathing and fear with which Mr. Utterson regarded him. (ch. 2)

There is a recurring pattern here by which Jeckyll's observations are reaffirmed by evidence given throughout the book. Hyde has a disconcerting effect on practically everyone who meets him: an intensely visceral reaction which transcends conscious understanding.

Robert Louis Stevenson explores the dual nature of man in this novel. He realized that man was created with warring natures - good and evil. Sometimes good overtakes man, sometimes evil. Man has a sin nature.

Dr. Jekyll was an upstanding scientist. He performed experiments for the good of society, but when left alone to his thoughts, he often obsessed over the fact that he also had an evil part of him that cared nothing for his fellow man. He did not like this evil side of himself especially, but it also was compelling to him. Both of these natures were truly him, but wouldn't it be nice if he could be happy when he was evil as well as be happy when he was good? If only he could separate the two!

“With every day, and from both sides of my intelligence… I thus drew steadily nearer to that truth, by whose partial discovery I have been doomed to such a dreadful shipwreck: that man is not truly one, but truly two… I saw that, of the two natures that contended in the field of my consciousness, even if I could rightly be said to be either, it was only because I was radically both.”

Ahaha! One night, he decides to concot a potion which will allow him to separate his two natures. That way, he could go from one nature to the other at will. At first, the good side is stronger. Whenever Jekyll got too caught up in his evil side, he could quickly drink the potion and get rid of Mr. Hyde, his alter ego. But before long, his good side grew weaker and he could no longer control his evil nature. Mr. Hyde began to transform Dr. Jekyll involuntarily until Mr. Hyde overpowered and finally destroyed the powerless Dr. Jekyll who by then was very sorry for what he had created, but alas, it was too late.

This is the great change of the story. The evil wins out because Dr. Jekyll's motives were not pure. He did it for ambition:

"Had I approached my discovery in a more noble spirit, had I risked the experiment while under the empire of generous or pious aspirations, all must have been otherwise, but at that time my virtue slumbered; my evil, kept awake by ambition, was alert and swift to seize the occasion.