There are many similes to describe what happens to Charleston in late May, when Spoleto Festival and Piccolo Spoleto Festival provide residents and visitors with all that arts programming.

It’s a spring blossoming when colorful annuals open their petals to us in warm welcome, inviting admiration.

It’s a clattering cavalcade of artists who traipse through the city throwing their confetti into the air and shouting for joy.

It’s a rebirth when the life force, fueled by expressions of art and philosophy and beauty, asserts itself and reminds us of who we are and where we come from.

Or it’s a sort of invasion, a temporary takeover of the peninsula where occupying forces bring culture to share and prompt a local response in kind — Piccolo Spoleto. In this last sense, the festivals are a battleground on which patrons vie for position and entertainers compete with one another to win their audience.

If Spoleto Festival introduces us to faraway cultures and practices, Piccolo Spoleto presents mostly local artists on their own turf, providing us a reminder of our great year-round fortune.

The occupying force helps build and reinforce the infrastructure, it helps set a high bar of achievement and it informs us about what’s happening in the wide world beyond Charleston so that we may have a frame of reference and better ability to assess the talent we’re exposed to.

Piccolo Spoleto maintains the infrastructure and builds upon it; it offers a range of artistic expression, from amateur theater to acclaimed musical performances; and it garners inspiration from great artists worldwide in order to thrill us and give us hope for more.

The invasion forces are here. The two festivals officially start tomorrow and run through June 7. Spoleto Festival will share Chinese art and culture (the opera “Paradise Interrupted”); jazz from South America (Monica Salmaso, Carlos Aguirre) and Italy (Musica Nuda, Rita Marcotulli and Luciano Biundini); drama from Shakespeare’s Globe (“Romeo and Juliet”); puppet theater, choral passions, new and old music, extravagant dance, garden tours, classic film, the graces of two extraordinary chanteuses and more.

Leave the armor and sword at home; this is a benevolent army of artists whose intentions are most honorable. They merely want to leave an impression.