Spiders are a big inspiration for Tomas Saraceno, a visionary artist whose immersive installations imagine a world of “more reciprocal relationships.” Telling stories about history and time, Saraceno questions everything: “What if we could talk to spiders?” he once asked. “Does the earth float, or does it fly?” In an installation that reaches from Palazzo Strozzi’s courtyard to its exhibition halls, Saraceno weaves a dialogue between Renaissance motifs and the contemporary world to create a powerful web. —E.C.