Isha's arrival provided The Emperor with enormous help. The goddess of life first helped The Emperor restore Terra's ecology, allowing this planet of nothing but deserts and war-torn wastelands to flourish with life once more. With Isha's help, Terra's agriculture advanced to an inconceivable level. The vast food output brought the living standards of the mortals under The Emperor's rule close to the Golden Age. This level of production even dealt a severe blow to farming businesses. Only merchants producing more complex foods, such as cake makers, could earn money from the public.
Most of the time, Terra's people only needed to toss fresh fruits and vegetables into a large pot and boil them in water to enjoy a fairly delicious meal.
Isha then drove the Imperium's progress in genetics. Although The Emperor and his scientists were already intelligent and hardworking enough, before Isha, who wielded authority over life itself, they were like someone brandishing a blade before Khorne—overestimating themselves.
Where scientists needed precise instruments and complex experiments to remove and add genes, Isha merely plucked them off and fitted them in with ease, as if the strings of genes before her were not genes at all, but a solid, visible tower of building blocks.
Isha did not like The Emperor's idea of replacing the Thunder Warriors with Space Marines. Treating life like a tool to be iterated, upgraded, and casually discarded disgusted her. Even the vast War in Heaven had not changed her sentimental nature.
Thus, Isha repaired the flaws of the Thunder Warriors, making their minds more controllable and mild rather than leaving them as machines that could only vent their passions through slaughter and war. This led The Emperor to completely abandon the long-brewing Astartes Project. After all, these warriors modeled on the genes of the Primarchs