public final void move(final Field f) {
        final Point goal =
            f.sanitizeCoordinates(direction.getCoordinate(position));

        if (!f.isWalkable(goal)) {
            return;
        }

        if (f.isGrass(goal)) {
            health += Parameter.HEALTH_PER_FOOD.getValue();
            f.removeGrass(goal);
        }

        position = goal;
    }