To borrow from the same Thomas Dolby song that she does in the play, Karen Zacarias essentially blinds us with science in her exceedingly intelligent and elaborately written “Legacy of Light.”

Part of the comedy takes place in 18th-century France, where the historic philosopher, poet and playwright Voltaire matches witticisms and academic theories with his “muse” (and lover), the influential but underappreciated scientist Emilie du Chatelet. And part of it is set in modern-day New Jersey, where, in a last resort to have a child, a renowned astrophysicist named Olivia and her humble husband, Peter, are interviewing prospective surrogate mothers.

Constantly alternating and drawing correlations between the past and the present, it doesn’t take long for Zacarias to make her most basic point about how far women and science have come. For Emilie, whose brilliant career is reduced to a footnote by the patriarchal prejudices of the day, another childbirth at age 42 is potentially life-threatening. For Olivia, the possibilities are endless -- artificial insemination, surviving cancer and being credited for discovering the “embryonic core” of a new planet. As she puts it to Peter, “If the galaxy can have a baby, why can’t we?”

At different times, various characters deliver highly articulate speeches about the laws of nature, the properties of light (and love), the brevity of life, the importance of making a contribution to the world and having the will to change it. But after laying everything on rather thickly with so many heady debates, the play’s second act feels forced and false. Zacarias strains to tie certain characters together even more directly. When, by some fantastical twist, Voltaire or Emilie suddenly appears to Olivia or Peter, it seems less magical than ridiculous.

Except for Joanna Schmink’s period costumes, there aren’t a lot of stylistic touches to sufficiently contrast then from now in director Susan Reid’s modest Horizon Theatre production. In a larger space, perhaps scenic designers Moriah and Isabel Curley-Clay could have done more to distinguish between time frames. As is, the characters circulate around a common set that is abstract, at best, and at worst fairly tacky.

As Isaac Newton might observe, for every action in Reid’s cast, there is an equal and opposite reaction: e.g., Leigh Campbell-Taylor is better portraying Emilie’s serene thoughtfulness than her sensuous volatility, while Allen Edwards’ Voltaire is easier to laugh with in his comedic moments than to take very seriously in his dramatic scenes.

Elsewhere in the ensemble, the women leave stronger impressions than the men, primarily because they have more to work with. Lane Carlock invests Olivia with a genuine sophistication that Robin Bloodworth’s Peter largely lacks (never mind his dual role as Emilie’s husband). Corey Bradberry plays Emilie’s cocky young lover and the hot-headed brother of Olivia’s surrogate, Millie.

Best of all is the luminous Kate Donadio as both the free-spirited Millie and as Emilie’s forward-thinking daughter. As conceived by Zacarias, the connection between her two characters may be contrived, but as performed by Donadio with such warmth and grace, it almost makes perfect sense.

Theater review

“Legacy of Light”

Grade: C+

Through May 8. 8 p.m. Wednesdays-Fridays; 8:30 p.m. Saturdays; 5 p.m. Sundays; 3 p.m. Saturdays (April 23 and May 7). $20-$35. Horizon Theatre, 1183 Austin Ave. (Little Five Points). 404-584-7450. horizontheatre.com.

Bottom Line: Greater in its high-minded cause than in its half-baked effect.