A crucible is a situation or place that forces people to make difficult decisions. It can also mean a situation of severe trial in which something is created through the interaction of different elements. This links to the play as

Rebecca Nurse advises Proctor and Putnam that they should ‘rather blame ourselves’ for the sickness of Betty than chase ‘loose spirits’. This shows that she feels that, if they start a witch hunt, the hysteria that will take over the town will be damaging. This shapes our reaction to Hale’s entrance as Rebecca tells us ‘I fear it’ – making the audience believe that Hale is a fraudster, looking to make any ailment into a symptom of witchcraft.