Physiology is a question of physical being, animal instincts and nature.

There is another degree of humanity also brought to light in the novel.  Before the affair begins, Laurent weighs up the advantages of becoming Thérèse’s lover.  This demonstrates that he is capable of thought and decision-making, two things that are not considered as animal traits.  Rational thought does not comply with the concepts of physiology thus illustrating that Thérèse Raquin has more meaning to it and can be read on another level.

When Zola speaks of ‘l’analyse du mécanisme humain’, he is suggesting that the human body is like a machine, with inputs and products, a completely scientific being without morals or judgements.  It has been shown already that Thérèse has some element of thought and self-control.  It can also be said that she does have a conscience and a sense of right and wrong and these are displayed through guilt.  The aspects of shame become clear after the murder of Camille.  Although this is portrayed through physical terms, the idea does come across, showing that the novel is not wholly physiological.  The guilt s represented by many factors including the bite mark on Laurent’s neck and more significantly the ghost of Camille, which becomes increasingly dominant in the lives of Thérèse and Laurent.  The accusing look of the false-jewellery seller and of the cat adds to this and show that the novel does have guilt entailed within it.  The way that the two characters shift the blame to one another also shows a sense of regret.  The idea of morality is represented as a message in Thérèse Raquin as it discourages readers from adultery and shows the consequences of it.

The prejudices of Zola’s era come forth in the novel.  For example, the text is written in such a way that Thérèse is frowned upon for her sexual nature whereas Laurent’s ‘need’ for sex is thought of as a normal characteristic of a man.  This is in itself a judgement, and opposes Zola’s intention for a purely physiological narrative.  He brings this idea, perhaps unintentionally into Thérèse Raquin. 

In addition to the idea of sexuality, sex itself seems to be condemned in the novel and the reader is left thinking of it as dirty.  An example of this occurs when Zola uses the verb ‘vautrer’ to describe Thérèse’s sexual posture.  This word carries judgemental attitudes with it and puts prejudice on Thérèse’s sexuality.  With these aspects of the text, it is clear to see that the novel is not entirely physiological.  Other aspects of vocabulary also contain judgmental factors even though there is a lot of medical lexis involved.  Whenever the narrator refers to Thérèse there is often a mention of the nervous system and nerves.  Thérèse is described as having a nervous temper and she often shakes when things go out of control.  Laurent, nevertheless, is described as being dominated by his blood and has an opposite temperament to Thérèse.  Although the descriptions of the protagonists are based on physiological, the way they are referred to is not.  For example, on the wedding night of Thérèse and Laurent the narrator addresses them as ‘les meurtriers’ and they have been denoted as ‘des assassins impunis’ in other texts.  These words are ones of judgement and this is not a feature of physiology therefore indicating the novel is not purely physiological.

As Taine commented, Thérèse Raquin can be seen as a partial account.  Only a small margin of society is presented in the book and therefore the social side is not covered adequately.  In order for the novel to be purely physiological, a large portion of the society needs to be included as it is important to show all aspects that would affect the lives of the protagonists.  For this, the novel cannot be purely physiological because nature and physiology involve more than just a handful of people.

The novel as a whole can be said to be a physiological work where the characters interact physically rather than mentally.  On looking further into Thérèse Raquin, it is possible to see some weaknesses in the physiology, as there are aspects involved that do not conform to the scientific idea.  Zola claimed that Thérèse Raquin was planned to be scientific and declared it a purely physiological piece of literature.  Many unscientific elements stand out from the scientific form and so it is possible to deduce that Thérèse Raquin is not a novel of physiology in its entirety.  Guilt, reason, remorse and morals have no place in physiology and there are many examples of these throughout the novel.  Even with these aspects of guilt and judgement, the reader is still able to read the novel scientifically, without sympathy for Camille.