Mater semper certa est

"Mater semper certa est" means that the mother is always certain. This phrase is usually used in reference to paternity, which means who the father of a child is. When a baby is born, it always has a mother because it grew inside her tummy. But sometimes it can be difficult to know who the father is because the baby could have been made by different men's sperm. However, the mother is always certain because she is the one who carried and gave birth to the baby. It's like when you make a cake, you know for sure that you made the cake because you did all the mixing and baking, even if you used different ingredients. So, no matter who the father is, we always know who the mother is because she carried the baby in her tummy and gave birth to it.