The nineteenth century title of the work applies primarily to the girl at the right of the filed who is bent over the writing woman's shoulder, peering at the letter as it takes shape. Whatever the full intentions of this woman are, she is certainly trying to discern truth, and rather impatiently at that. Whether or not she is having more luck than the viewer of this work is hard to say, given her neutral facial expression and the lack of concern of the other two individuals in the painting. It is impossible to say what is in the letter, or whether the curious woman approves of what she reads or not, or in what way (if any) the news that the letter carries has an effect on her. Other details of the painting provide further clues, however. The curious woman also appears o be the youngest of the group. The one who is seated and engaged in writing wears a head cover and the most conservative gown of the three, signaling that she is more settled than the other two and almost certainly married. It is likely, then, that the other two are not married, and this letter could very weel have something to do with a suit for one of these other women's hands -- most likely the third woman in the painting, dressed. This woman is at once the least interesting ad most intriguing figure in the painting -- she is not doing anything (not even reading over someone's shoulder), but she is given the most light and the tallest position, signaling her importance. Her position under the painting also solidifies her status as an object of desire, and the difficulty one finds in trying to read her face is mirrored in the difficulty of trying to discern any details of the painting. It is likely she for whom the letter is being written.

The over-the-shoulder reading of the...

This interpretation is strengthened by the fact that the youngest sister (according to the age determinations made here) is in the most shadowy part of the room, suggesting something hidden and perhaps even sinister in her intentions. Also, this figure is dressed in green, the traditional color of jealousy, and Ter Borch was known to include use of many symbolic elements in his paintings (76). The watch could be seen as another symbolic elements; the youngest sister's jealousy would stem from her awareness of the passage of time without bringing a husband (or lover) for her, and the watch is a physical reminder of time's continual flow.
This, then, is one possible explanation for what is going on in this painting: the woman in pink received a letter from a suitor which lies on the table. Her sister and guardian is composing a measured yet encouraging letter in response while the pink sister reflects dreamily on her future as a wife. Meanwhile, the younger sister is jealously reading the response and wishing it was she who had been courted and would soon be married. The other sisters remain completely oblivious to this jealousy of the youngest sister, which will only make her jealousy sharper in the future. Whether or not this is what Ter Borch intended will never be known -- all viewers of this painting will have to contain their curiosity.