You mentioned in your talk that astrology is a form of magic, so what is magic?
The Scholars said magic tantamount to everything that is subtle and whose cause is hidden, so as to have a hidden influence not to be known by the people. In this respect, its meaning comprises both astrology and divination. Rather, it includes influence by way of eloquence and fluency of speech, as the Prophet () said: “Verily, some forms of speech are magic.”64 So, everything exerting influence, yet it is not something known, then it, i.e. the influencing factor, is a kind of magic.
64 Collected by al-Bukhaaree in his Saheeh, vol.7, no.662, Muslim and others.