Side by side on the zodiac and worlds apart in temperament - that's Capricorn and Aquarius, two signs that share a border but not a language. The semisextile between them is a study in mild mismatch: no lightning-strike recognition, just the slightly effortful business of two people who prize very different things learning to make sense of each other. Interestingly, both used to answer to Saturn before Aquarius got Uranus, so there's a buried family resemblance under all the difference - a shared respect for principle, expressed in almost opposite ways.
What Capricorn and Aquarius each trust
The element split does most of the work. Earthy Capricorn trusts what's proven, wants results you can measure, and builds toward a tangible future; airy Aquarius trusts the idea, the theory, the reform that hasn't happened yet, and cares more about being right in principle than rewarded in fact. Capricorn can find Aquarius impractical, a head full of blueprints for buildings nobody's funded; Aquarius can find Capricorn conventional, too willing to work inside a system that ought to be replaced. Each is the corrective the other resists - Capricorn grounds the vision, Aquarius keeps the ambition from ossifying into mere status-climbing.
The initiator meets the immovable
The modes add a specific standoff. Cardinal Capricorn moves to take charge and set the plan; Fixed Aquarius won't be led anywhere it hasn't independently decided to go. So Capricorn pushes and Aquarius simply doesn't budge - not out of laziness, but out of principle, which is far harder to argue with. The initiator meets the immovable, and the only way through is Capricorn learning that Aquarius can't be managed into agreement, and Aquarius conceding that some plans need a driver.
Beyond the sun signs
Platonically, they make a strong, dry, mutually respectful pair - the two who take each other's ideas seriously and don't waste words. As lovers it asks for patience with a rhythm that never quite syncs on its own. Remember that two aligned Suns is the smallest promise two charts can make to each other; the real compatibility is written in the lunar fit, the Venus signs, and the way each Mars wants to be approached.