The number seven symbolizes the concept of teva or nature. There are seven days of the week that embody the normal cycle of living. By contrast, the Maharal explains the number eight symbolizes lemala min hateva, or ascending above the natural to the supernatural. A bris mila is required on the eighth day from birth. It represents a partnership between ourselves and G-d which is something above nature. That Hashem allows us to ‘perfect’ the child and contribute to his handiwork is something inexplicable.
Additionally, we have a seven week cycle from Pesach to Shavuos. Seven weeks of seven days equals forty-nine. On the fiftieth day, we celebrate the giving of the Torah to the Jewish people which is emblematic of transcendence. The angels were upset that G-d gave the Torah to man. Torah is from a world-beyond and the angels couldn’t fathom G-d selecting to give it to those of the earthly abode. G-d had to persuade the angels that we were worthy of such a gift.
The Ramban suggests the miraculous is hidden within the mundane. That teva itself is really all miracles. That we wake up, breath, survive and thrive is all miraculous. Nothing can ever be taken for granted.
In the precarious times in which we live, every moment is precious and every day is miraculous. To me, the numbers seven and eight are combined and unified as one. We just have to open our eyes to see it.