What does Jekyll and Mr. Hyde tell us about evil? Does the indulgence of pleasures automatically lead to evil or is evil inherent in all human beings? Where does pleasure fit in here?
My take is a bit different. My opinion is that Stevenson is saying that every human being has both good and evil within them, the duality spoken of above. But the problem is not making choices, but accepting our not-so-laudable dark side. Yes, there is choice involved, but the larger issue is repression and denial of "sinful" feelings. Desire, if repressed, as was the overwhelming case in the Victorian era, lead to unheathly outlets for desire, no matter what the person's socio-economic level. Without a venue for the release of desire and the fulfillment of want, giving in a little to "sin" can easily overwhelm us, as it did Jekyll.
Vladamir Nabokov has a fantastic analysis of the nature of man in Stevenson's novella. See "Studies in Literature."
For an interesting discussion of the problems of desire, see Adam Phillips study, "Side Effects."
Dr. Jekyll and Mr. Hyde demonstrates the duality of man's nature, and it is the choices we make that determine good or evil. Henry Jekyll is a product of the upper social class in Vctorian Society in which there were certain behaviors that were expected of a 19th century gentleman. These social niceties excluded certain pleasurable indulgences that Jekyll wished to partake in. Stevenson never elaborates on what pleasures Jekyll wished to indulge, but 19th century readers could imagine all sorts of behaviors that would have been considered scandalous for a proper gentleman. Since Jekyll wished to maintain his reputable standing in society as well as indulge in forbidden pleasures, he created his potion to allow him to partake in both worlds. Unfortunately, Mr. Hyde (the hidden hedonistic part of Jekyll's personality) became too much of a temptation for Jekyll, and like any addiction, got out of control.
Indulging in pleasurable activities is not an automatic path to evil. Society determines what is and what is not acceptable behavior based on primarily religious attitudes; however, since Stevenson did not elaborate, who is to say what Jekyll's temptations were. It is when the pursuit of pleasure is out of control and causes suffering to ourselves or others that it could become a problem. Drinking alcohol in itself is not a sin, but driving a car while intoxicated is totally irresponsible. Choice is the key factor.