The image is an illustration for one of the fables written by Jean La Fontaine (1621-1695), 'The astrologer who stumbled into a well'. The tale, which attacks astrology as a means of predicting the future, opens with the words:

An Astologer once fell
incontinently down a well.
'How can you claim to read the sky,
poor fool, who cannot keep your eye
on where your feet are!', came the cry

According to La Fontaine, the astrologer is so engrossed with fruitless his musings about the future that he does not see what is right in front of him. Although the original fable does not mention a telescope, merely those who observe the heavens as a predicitive tool, many editions included images of the astrologer further distracted by the instrument, still looking through it as he falls into the well. The idea of the natural philosopher or scientist distracted from practical earthly concerns as he looks through his telescope was already well established by the late seventeenth century.