慈 appears in many classical compounds: 慈悲 (compassion/mercy), 慈善 (charity), and 慈禧 (Empress Dowager Cixi, whose name uses this character). As a standalone character it is more literary/classical than colloquial.
memory
Think of 慈 as two 幺 (threads) over 心 (heart) - a heart entwined with tender threads of care.
心 depicts a heart with its chambers. As radical underneath, it grounds 慈 in the emotion family - kindness flows from the heart. It is one of Confucianism's core virtues, tracked as a quality of feeling rather than action.
兹 supplies the sound (zī drifted to cí). The same phonetic powers 滋磁孳. It originally depicted growing shoots - twin tufts sprouting - a faint flavor of nurturing growth that fits the maternal warmth of compassion.
