Why does it seem that Mr. Rochester, in Charlotte Bronte's novel Jane Eyre, does not really want to see Mr. Mason? Is he afraid that Mr. Mason will tell the secret to other people?
In Chapter 18 of Jane Eyre, Mr. Mason arrives from the West Indies. Jane notes that Rochester is upset upon hearing that Mason is visiting. She also learns that Rochester spent time in the West Indies.
Later, Mr. Mason is wounded in the arm, and Jane tends to him. Rochester tells Jane and Mr. Mason, "You will not speak to him on any pretext—and—Richard, it will be at the peril of your life if you speak to her: open your lips—agitate yourself and I’ll not answer for the consequences" (page numbers vary by edition). Rochester is warning Mr. Mason not to tell Jane that Bertha, who is Mr. Mason's sister, is in the attic. Mr. Rochester is afraid that Mr. Mason will reveal Bertha's existence to Jane. Rochester clearly cares for Jane at this point, so he does not want her to leave Thornfield if she finds out about Bertha. In addition, at this point, Rochester seems to be considering marrying Blanche, and the revelation of Bertha's existence would prevent this marriage. If Mason tells others that Bertha exists, Rochester will not be able to marry again.
In Charlotte Brontë’s Jane Eyre, there are several reasons why Mr. Rochester is made uncomfortable by the arrival of Mr. Mason, the brother of Rochester’s mad wife, Bertha Mason.
The main reason is that he would like to get married again. At this point in the story, he appears to be interested in marrying Blanche Ingram, although he is falling on love with Jane Eyre and increasingly would prefer to marry her.
As both bigamy and divorce were illegal, Rochester cannot be remarried if it is known that Bertha is alive and his legitimate wife. Since he married in the West Indies, only Mr. Mason knows that Bertha is his wife and can prevent his remarriage. Rochester’s fears are, in fact, correct, as Mr. Mason later interrupts his marriage ceremony with Jane Eyre.
There are several reasons that Mr. Rochester does not want to see Mr. Mason. First, Mr. Mason knows about Mr. Rochester's real wife, Bertha Mason. Mr. Rochester is afraid that Jane and others will discover that he is already married to a madwoman.
Second, Mr. Mason is a reminder of Mr. Rochester's past. Just as Jane and Rochester fall in love with each other and plan to get married, Mr. Mason threatens to reveal past secrets that would ruin their happiness. For the first time in many years, Mr. Rochester has a chance to be happy once again. He believes that Jane is a chance for him to redeem the wreck his life has become.
You are correct in believing that Mr. Rochester is afraid that Mr. Mason will tell his secret to other people. The revelation of his secret would ruin both his reputation and the fragile hope for happiness he has built with Jane.